Class 8

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Class 8 Basic Science Chapter 14 Water Question Answer Notes

Class 8 Basic Science Chapter 14 Notes Kerala Syllabus Water Question Answer

Water Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
What changes will occur on heating water that has already reached boiling point?
Answer:
When water has reached its boiling point (100°C at 1 atm pressure), further heating will cause it to change state from liquid to gas (steam). The temperature will remain constant at the boiling point during this phase change, as the extra heat energy (latent heat) is used to overcome the forces of attraction between water molecules.

Question 2.
Explain how the boiling point of water varies under the following conditions:
a. In high-altitude areas:
b. At sea level:
c. In vacuum containers:
d. In pressure cookers:
Answer:
a. In high-altitude areas, the atmospheric pressure is lower. A decrease in pres¬sure causes the boiling point of water to decrease (become lower than 100°C).

b. At sea level, the atmospheric pressure is considered normal (approximately 1 atm). Under this standard pressure, the boiling point of water is 100°C.

c. In vacuum containers, the pressure is significantly reduced. This drastic decrease in pressure will cause the boiling point of water to decrease considerably, potentially allowing it to boil even at room temperature or lower.

d. In pressure cookers, steam is trapped, causing the pressure inside to increase. An increase in pressure causes the boiling point of water to increase (become higher than 100°C, e.g., 120°C).

Question 3.
Due to the intermolecular attraction between water molecules, a force arises that tends to minimize the surface area of water. How can this be demonstrated?
Answer:
This force is surface tension. It can be demonstrated in several ways:

1. Floating a Blade/Needle: Gently place a razor blade or a needle flat on the surface of still water. Due to surface tension acting like a stretched skin, the blade/needle can float even though it’s denser than water.
2. Water Striders: Observe insects like water striders walking on the surface of a pond. They distribute their weight, and the surface tension supports them.
3. Spherical Drops: Observe water drop¬lets on a surface that water doesn’t wet (like a lotus leaf or plastic sheet). Surface tension pulls the water into a shape with the minimum possible surface area, which is a sphere.
4. Soap Film Experiment: Dip a wire ring with a thread tied across it into soap solution. Break the soap film on one side of the thread. The surface tension of the remaining film will pull the thread into a curved arc, minimizing the film’s surface area.

Question 4.
Write any three special properties of water and explain situations in daily life where we make use of these properties.
Answer:
High Heat Capacity:
Property: Water can absorb a large amount of heat without a significant rise in its own temperature.
Application: It is used as a coolant in vehicle radiators to absorb excess engine heat and prevent overheating. It also helps regulate body temperature.

Universal Solvent:
Property: Water can dissolve a wide variety of substances.
Application: This allows us to make various solutions for daily use (like salt water, sugar syrup, medicines), enables nutrients to be transported in living organisms (in blood, plant sap), and unfortunately, also contributes to water pollution as harmful substances dissolve in it.

Anomalous Expansion (Ice Floats):
Property: Unlike most substances, water expands when it freezes into ice, making ice less dense than liquid water.
Application: Because ice floats, lakes and rivers freeze from the top down. The surface ice layer insulates the water below, allowing aquatic life to survive during winter in cold climates.

Question 5.
Observe the picture.
Compare the attraction between water molecules and the attraction between water and other substances, and explain why the water level rises inside a glass tube.

Answer:
The picture shows capillary rise.
Forces Involved:
Cohesion: The attraction between water molecules themselves.
Adhesion: The attraction between water molecules and the molecules of the glass tube.
Explanation: In the case of water and glass, the adhesive force (attraction between water and glass) is stronger than the cohesive force (attraction between water molecules). This stronger attraction pulls the water molecules up along the surface of the glass tube, causing the water level inside the narrow tube to rise above the level in the surrounding beaker.

Basic Science Class 8 Chapter 14 Question Answer Kerala Syllabus

Question 1.
Why does the panchayat give importance to the conservation of water resources? (Discussion)?
Answer:
The panchayat gives importance to water conservation because water is essential for the origin and survival of life on Earth. Water is crucial for agriculture, industry, energy production, and transportation. Conserving water bodies like wells, streams, and rivers, which are the wealth of the country, is a collective responsibility to protect this resource from pollution and ensure its availability for vital functions and growth.

Question 2.
Why do people think that if there is water, there is a possibility of life? (Discussion)
Answer:
People believe that where there is water, there is a possibility of life because water is the precious gift of nature responsible for the origin and survival of life on Earth. Water is essential for all vital functions in living organisms, such as respiration, digestion, and excretion, as well as maintaining body temperature and keeping eyes moist. Plants also need it for growth and photosynthesis. This fundamental necessity is why scientists search for water when looking for life on other planets.

Question 3.
What are the uses of water?
Answer:

1. For drinking.
2. For bathing.
3. For cooking.
4. It’s also essential for vital functions like respiration, digestion, and excretion, regulating body temperature, and keeping eyes moist.
5. It’s needed for plant growth and photosynthesis.
6. It is crucial for agriculture, industry, energy production, and transportation.

Question 4.
Why can water be used for so many purposes?
Answer:
Water can be used for so many purposes primarily because of its special property as a universal solvent. Water can dissolve a wide variety of substances, and the nature of the water changes depending on what is dissolved in it, allowing it to be used to make different types of solutions. This solubility is one of solubility is one of the main reasons for its varied uses.

Textbook Page No : 235 & 236

Question 5.
Complete the Table (Table 14.1 – Litmus Test)

Answer:

Pure Water / Substance Added to Water	Blue / Red Litmus Paper Experiment – Observation	Inference
Pure Water	No change in the colour of the litmus paper	Water has no acidic or basic property.
Common Salt	No change	Common Salt solution is Neutral
sugar	No change	Sugar solution is Neutral
honey	No change	Honey solution is Neutral
vinegar	Turns blue litmus red	Vinegar solution is Acidic
Soap Powder	Turns red litmus blue	Soap Powder solution is Basic
Lime juice	Turns blue litmus red	Lime juice solution is Acidic
Sodium hydroxide (Alkali)	Turns red litmus blue	Sodium hydroxide solution is Basic

Question 6.
What could be the reason for the hardness of water? (Discussion)
Answer:
The hardness of water is caused by dissolved salts that water picks up as it flows through the soil. Specifically, the hardness is caused by some salts of metals like magnesium and calcium. If the hardness is caused by bicarbonates of calcium and magnesium, it is temporary hardness. If it is caused by sulphates or chlorides of metals such as magnesium or calcium, it is permanent hardness.

Question 7.
Complete the Table (Table 14.2 – Hardness Test)

Answer:

Substance added to water	Soap lathers well/ Doesn’t lather well	Conclusion
Pure water (nothing added)	Lathers well	Pure water is soft water.
Magnesium bicarbonate/ Calcium bicarbonate	Doesn’t lather well	These salts cause hardness.

Question 8.
How does the water level appear inside the glass tube? (Question from Experiment)
Answer:
The water level inside the thin glass tube appears to be higher than the water level in the beaker. This phenomenon is due to capillary action.

Textbook Page No : 237

Question 9.
Now pour a little water on a leaf of colocasia. Does it wet the surface?
Answer:
No, the water does not wet the surface of the colocasia leaf easily.
Explanation: The reason is that the molecules in the leaf and the water molecules have very little attraction between them (poor adhesion).

Question 10.
Can you list some materials around you that water cannot wet? (Discussion)
Answer:
Water does not wet a surface when the attraction between the molecules in the surface and the water molecules is very little.
Materials that water cannot easily wet (hydrophobic materials) include:

1. A colocasia leaf.
2. Waxy or oily surfaces (like a car that’s been waxed).
3. Plastic or synthetic materials (like a plastic sheet, which is why drops are spherical).
4. Teflon (used in non-stick pans).
5. The feathers of some water birds due to their oily coating.

Question 11.
What is the shape of the water drops (on a plastic sheet)?
Answer:
If a surface is not getting wet, the water drops will be spherical in shape. This occurs because the attraction between water molecules (cohesion) is stronger than the attraction between water and the surface (adhesion).

Question 12.
Why is the water surface behaving like this (when coins are added)?
Answer:
The water surface will appear to bulge or rise above the rim of the beaker, behaving like a stretched, elastic film or membrane.

Question 13.
Why is the water surface behaving like this?
Answer:
The water surface is behaving like this due to surface tension. The mutual attraction between water molecules causes a force to act on the water surface, making it behave like a stretched film.

Question 14.
Why can some insects walk on the surface of water?

Answer:
Insects can walk on water because of surface tension. The mutual attraction between water molecules creates a force that makes the water surface behave like a stretched, flexible film, which is strong enough to support the light weight of the insects.

Question 15.
Gently place a blade on the surface of water. Can you explain why the blade stays on top without sinking?

Answer:
The blade stays on top of the water without sinking because of surface tension. The mutual attraction between water molecules creates a force at the water surface that makes it behave like a stretched film. This stretched film is strong enough to support the light weight of the blade without breaking.

Textbook Page No : 238 & 239

Question 16.
From the figure can you say in which direction the force acts on the water molecules on the surface? (Discussion)
Answer:
Based on the text explaining surface tension, the force acts on the water molecules on the surface in a direction that tries to minimize the surface area. This force is an inward pull (towards the bulk of the liquid), which causes the surface to behave like a stretched film.

Question 17.
What is the shape of the soap film now (after breaking it on one side of the thread)?
Answer:
When the soap film on one side of the thread is broken, the remaining film on the other side will pull the thread, causing the thread to take a circular or curved shape that maximizes the area of the side where the film remains, and minimizes the area of the film itself. The intact film pulls the thread to try and reduce its own surface area.

Question 18.
Is it easier to clean dirty clothes with plain water or with soap water? Clothes get cleaner in cold water or hot water? (Discussion)
Answer:
It is easier to clean dirty clothes with soap water and hot water.

• Plain water has a high surface tension, meaning it doesn’t easily wet the clothes.
• When you add soap or heat the water, the surface tension decreases.
• This decrease in surface tension allows the water to wet the clothes better and clean them more easily, helping the water penetrate the fabric and lift the dirt.

Question 19.
What change happens to water at this point (when temperature stops increasing despite continued heating)?
Answer:
At this point, the water starts to boil. The water molecules begin to change their state from liquid to gas (steam). This temperature is the boiling point of water, which is 100°C (at normal atmospheric pressure).

Question 20.
Why doesn’t the temperature rise once the water starts boiling?
Answer:
Once water starts boiling, the temperature doesn’t rise because the extra heat energy is used to overcome the force of attraction between the water molecules. In other words, the heat is used for the change of state (liquid to gas) rather than to increase the temperature of the liquid water.

Question 21.
Which contains more energy boiling water or steam? Which can cause severe burn? Boiling water or steam? (Discussion)
Answer:
Steam contains more energy than boiling water. The extra heat energy (called latent heat of vaporization) added to boiling water to turn it into steam without increasing the temperature is stored in the steam. Therefore, steam can cause a more severe burn. When steam condenses back into liquid water on the skin, it releases that extra latent heat, causing a much more intense burn than boiling water at 100°C.

Textbook Page No : 240

Question 22.
Why does cooking in open vessels take more time in high mountain regions? (Discussion)
Answer:
In high mountain regions, the atmospheric pressure is lower because height increases as pressure decreases. Since the boiling point of a liquid is related to atmospheric pressure, when the pressure decreases, the boiling point of water also decreases. This means water boils at a temperature lower than 100°C. Food takes longer to cook because the boiling water, the medium of cooking, is at a lower maximum temperature.

Question 23.
What change happens to the boiling point when pressure increases? How does cooking become easier in pressure cookers?
Answer:

• When pressure increases, the boiling point of water increases.
• Cooking becomes easier in pressure cookers because they are sealed and the steam cannot escape. As a result, the pressure inside increases. This increased pressure raises the boiling point of the water well above 100°C. Cooking at a higher temperature significantly reduces the cooking time.

Question 24.
When the same amount of heat is given to water and coconut oil, which one’s temperature rises faster in a fixed time? Why?
Answer:
The coconut oil’s temperature will rise faster.

• This is because water is a liquid with a very high heat capacity.
• Heat capacity is the amount of heat energy required to raise the temperature of a given substance by 1 °C.
• Due to its high heat capacity, the temperature of water does not rise quickly.

Question 25.
How can we make use of high heat capacity of water?
Answer:
The high heat capacity of water is utilized in the following ways:

• Water is used to cool hot objects.
• The radiators in vehicles use a mixture containing a special coolant and water to cool the engine.
• Water helps in maintaining the body temperature within a limit.

Textbook Page No : 241

Question 26.
In which state is oxygen usually seen? What about hydrogen? But in which state is water usually found?
Answer:

• Oxygen is usually seen in the gaseous state.
• Hydrogen is usually seen in the gaseous state.
• Water is usually found in the liquid state.

Question 27.
What could be the reason for water to occur in the liquid state?
Answer:
The reason water occurs in the liquid state at room temperature, even though its components (hydrogen and oxygen) are gases, is the existence of a special kind of attractive force between water molecules. This attractive force is strong enough to keep the water in a liquid form at room temperature.

Question 28.
Now think, what would happen if this force between water molecules did not exist?
Answer:
If the attractive force between water molecules did not exist, water would stay only in the gaseous state. The gas would not condense to form liquid water, meaning there would be no rivers, no seas, and probably no living things on earth.

Textbook Page No : 242

Question 29.
What happened to the volume of the water in the bottle when it turned into ice?
Answer:
When water turns into ice, its volume increases. This is an unusual property for a substance when cooled.

Question 30.
Can you now explain why a piece of ice floats on the surface of water when you put it in water?
Answer:
A piece of ice floats on the surface of water because its density decreases when it turns from liquid water into solid ice. This is because, unlike most substances, the volume of water increases when it freezes. Since density is mass divided by volume (D = m/V), an increase in volume for the same mass results in a lower density. Since the density of ice is less than that of liquid water, it floats.

Question 31.
What if the water in rivers and lakes there turns completely into ice? Wouldn’t aquatic life get trapped in the ice and die? Does that happen? What could be the reason?
Answer:
Aquatic life generally does not get trapped and die because the rivers and lakes do not freeze completely from top to bottom. The reason is:

• The maximum density of water is at 4°C. As the surface water cools to 4°C, it sinks, and warmer water rises.
• Once the surface water cools below 4°C and starts freezing, its volume increases, and its density decreases.
• This less-dense ice (and near-freezing water) floats on top, forming an insulating layer that protects the underlying water from freezing completely. This allows fish and other aquatic life to survive in the colder regions.

Textbook Page No : 243

Question 32.
What could be the reasons for water pollution?
Answer:

• Chemicals from agricultural fields.
• Chemicals from factories.
• Oils from vehicles.
• Other reasons not explicitly listed but implied by the images are dumping of solid waste into water bodies and the release of untreated sewage/industrial discharge.

Question 33.
What are the main problems caused by water pollution?
Answer:

• Destruction of aquatic plants.
• Damage to the food chain.
• Soil pollution.
• Diseases.
• Millions of people suffer from water-borne diseases every year, leading to many deaths, and a lack of access to clean water.

Class 8 Basic Science Chapter 14 Question Answer Extended Activities

Question 1.
Investigate and prepare a study report on the efforts taken in your locality to conserve water sources.

Question 2.
Based on rainfall availability across Kerala, prepare a rainfall distribution map.

Water Class 8 Notes

Class 8 Basic Science Water Notes Kerala Syllabus

The Importance of Water
Water is a precious gift of nature, and its conservation is a collective responsibility. The presence of water is what scientists look for on other planets (like the Moon) as evidence for the possibility of life.

Why water is essential:

• For Life (ജീവന്റെ നിലനിൽപ്പിന്):
  1. Water is responsible for the origin and survival of life on Earth.
  2. It’s essential for vital bodily functions like respiration, digestion, and excretion.
  3. It helps to regulate body temperature and keeps the eyes moist.
  4. Plants need water for growth and photosynthesis.
• For Development (വികസനത്തിന്):
  • Water is crucial for agriculture, industry, energy production, and transportation.
• Daily Uses: We use water for drinking, bathing, cooking, and many other purposes.

ഭൂമിയിലെ ജീവന്റെ ഉത്ഭവത്തിനും നിലനിൽപ്പിനും ജലം അത്യന്താപേക്ഷിതമാണ്. ദഹനം, ശ്വസനം തുടങ്ങിയ ശാരീരിക പ്രവർത്തനങ്ങൾക്കും കൃഷി, വ്യവസായം, ഊർജ്ജ ഉത്പാദനം തുടങ്ങിയ കാ ര്യങ്ങൾക്കും ജലം കൂടിയേ തീരൂ. അതിനാൽ, നമ്മുടെ ജലസ്രോതസ്സുകളെ (കിണറുകൾ, പുഴ കൾ) മലിനീകരണത്തിൽ നിന്ന് സംരക്ഷിക്കേണ്ട ത് നമ്മുടെ എല്ലാവരുടെയും ഉത്തരവാദിത്തമാണ്.

Characteristics of Water: Solubility (ജലത്തിന്റെ സവിശേഷത ലായകത്വം)
One of the most important characteristics of water is its ability to dissolve many other substances.

• Universal Solvent (സാർവിക ലായകം):
  • “Since water can dissolve a wide variety of substances, it is known as universal solvent”.
• Nature of Pure Water:
  • Observation: Pure water shows no change in the colour of blue or red litmus paper.
  • Inference: This means pure water has no acidic or basic property; it is neutral.
• Nature of Solutions:
  • The nature of water changes depending on the substances dissolved in it. If you dissolve an acid (like vinegar), the solution becomes acidic. If you dissolve a base (like soap), the solution becomes basic.

ധാരാളം പദാർത്ഥങ്ങളെ ലയിപ്പിക്കാൻ (dissolve) ജലത്തിന് കഴിവുണ്ട്. ഈ സവിശേഷതകൊ ണ്ടാണ് ജലത്തെ “സാർവിക ലായകം’ (Universal Solvent) എന്ന് വിളിക്കുന്നത്. ശുദ്ധജലം (Pure water) നിർവീര്യമാണ് (netural), അതായത് ഇതിന് ആസിഡിന്റെയോ ബേസിന്റെയോ സ്വഭാ വമില്ല. എന്നാൽ ജലത്തിൽ ലയിക്കുന്ന പദാർത്ഥം ഏതാണോ, അതിനനുസരിച്ച് ആ ലായനിയുടെ സ്വഭാവം (ആസിഡ് ബേസ്) മാറുന്നു.

Litmus Test Observations (Indicating pH Nature)

Substance Added to Water	Inference
Pure Water, Common Salt, Sugar, Honey	Neutral (No change in litmus paper color)
Vinegar, Lime juice	Acidic (Turns blue litmus red)
Soap Powder, Sodium hydroxide	Basic (Alkaline) (Turns red litmus blue)

Hard Water and Soft Water (കഠിനജലവും മൃദുജലവും)

• Soft Water: Water in which soap lathers well. Example: Rainwater.
• Hard Water: Water in which soap does not lather well. Example: Bore well water.
• Cause of Hardness: As water flows through the soil, salts of metals like magnesium and calcium dissolve in it. These dissolved salts make the water hard.

സോപ്പ് എളുപ്പത്തിൽ പതയുന്ന ജലമാണ് മൃദു ജലം (ഉദാ: മഴവെള്ളം). സോപ്പ് എളുപ്പത്തിൽ പ തയാത്ത ജലമാണ് കഠിനജലം (ഉദാ: കിണറ്റിലെ വെള്ളം). ജലം മണ്ണിലൂടെ ഒഴുകുമ്പോൾ, കാൽ സ്യം, മഗ്നീഷ്യം എന്നിവയുടെ ലവണങ്ങൾ (salts) അതിൽ ലയിക്കുന്നതാണ് ജലം കഠിനമാകാൻ കാരണം.

Types of Hardness

Type of Hardness	Cause	Removal Method
Temporary Hardness	Bicarbonates of calcium and magnesium	Removed by boiling the water.
Permanent Hardness	Sulphates or chlorides of metals such as magnesium or calcium	Cannot be removed by boiling.

Capillary Rise

• Capillary Rise (Fig 14.3): The water level inside a thin glass tube is higher than the water in the beaker.

Reason: Aattraction between water and glass is stronger than the attraction between water and water, so the water is “pulled up” the glass tube.

• Water on a Leaf (Fig 14.4): Water forms spherical drops on a colocasia (ചേസില) leaf and does not wet it.

Reason: Attraction between water and the leaf is very weak. Therefore, the water’s its attraction to itself is stronger, pulling the water into a tight, spherical drop.

Surface Tension (പ്രതലബലം)

• The surface of the water behaves like a stretched film or membrane.
• “Due to the mutual attraction (cohesion) between water molecules, a force acts on the water surface, making its surface area as small as possible. This force is called surface tension.”
• Surface Tension and Cleaning:
  1. Water has a high surface tension, which prevents it from “wetting” clothes easily.
  2. To clean clothes, we need to reduce this tension. We can do this by:
     • Adding soap or detergent
     • Heating the water (using hot water)
  3. This decreases the surface tension, allowing the water to soak into the fabric and clean more effectively.

Boiling Point (തിളനില)

• The boiling point is the specific temperature at which a liquid (like water) starts to change into a gas (steam).
• Boiling Point of Water: 100°C.
• Phenomenon: When water reaches 100°C and starts to boil, its temperature stops increasing, even if you continue to add more heat.
• Reason: This extra heat energy is not used to raise the temperature. It is used to overcome the forces of attraction between the molecules and complete the change of state from liquid to gas.
• Application:
  1. Steam (at 100°C) contains more energy than boiling water (at 100°C) because it holds this extra “hidden” heat.
  2. This is why steam causes more severe burns than boiling water.

ജലം തിളയ്ക്കുമ്പോൾ (100°C-ൽ), നാം തുടർ ന്നും ചൂട് നൽകിയാലും അതിന്റെ താപനില (temperature) കൂടുന്നില്ല. ഈ അധിക ഊർജ്ജം ഉപയോഗിക്കുന്നത് ജലം നീരാവിയാക്കി (change of state) മാറ്റാനാണ്. ഈ ‘ഒളിഞ്ഞിരി ക്കുന്ന’ ഊർജ്ജം (ലീനതാപം) കൂടി നീരാവിയി ൽ ഉള്ളതുകൊണ്ടാണ്, തിളച്ച വെള്ളത്തേക്കാൾ കൂടുതൽ പൊള്ളൽ നീരാവി ഏൽപ്പിക്കുന്നത്.

Pressure and Boiling Point (മർദ്ദവും തിളനിലയും)
□ The boiling point of a liquid is directly related to the atmospheric pressure acting on it.

□ Standard Boiling Point: The boiling point of water is 100°C at the normal atmospheric pressure of 1 atmosphere (1 atm).

□ Relationship:

1. Pressure Decreases → Boiling Point Decreases:

• Experiment (Fig 14.8): Water is boiled and the flame is turned off. When the piston of a syringe is pulled back, the pressure inside the tube decreases. This causes the water to start boiling again, even at a lower temperature.
• Application: In high mountain regions, the atmospheric pressure is low. Because pressure is low, water boils at a lower temperature (e.g., 80°C or 90°C). This temperature is not high enough to cook food properly, so cooking takes more time.

2. Pressure Increases → Boiling Point Increases:
Application (Pressure Cooker, Fig 14.9): A pressure cooker traps the steam, not allowing it to escape. This causes the pressure inside to increase significantly. Because the pressure is high, the boiling point of the water increases (e.g., to 120°C). Food cooks much faster at this higher temperature.
മർദ്ദം (Pressure) കൂടുമ്പോൾ തിളനില (Boiling Point) കൂടുന്നു; മർദ്ദം കുറയുമ്പോൾ തിളനില കുറയുന്നു.

പ്രഷർ കുക്കർ. ഇതിനുള്ളിൽ മർദ്ദം കൂടുന്നതുകൊ ണ്ട്, ജലം 100°C യിലും ഉയർന്ന താപനിലയിൽ (e.g., 120°C) തിളയ്ക്കുന്നു. ഇത് ആഹാരം വേഗത്തിൽ പാകം ചെയ്യാൻ സഹായിക്കുന്നു.

ഉയർന്ന മലനിരകൾ; അവിടെ മർദ്ദം കുറവായതിനാ ൽ, ജലം 100°C യിലും താഴ്ന്ന താപനിലയിൽ തിളയ്ക്കുന്നു. അതുകൊണ്ട് ആഹാരം പാകമാ കാൻ കൂടുതൽ സമയം എടുക്കുന്നു.

Heat Capacity of Water (ജലത്തിന്റെ തിളനിലയും)

• Observation: When the same amount of heat is given to equal masses of water and coconut oil, the coconut oil’s temperature rises faster. The water’s temperature rises very slowly.
• Reason: Water has a very high heat capacity.
• Heat capacity is the amount of heat energy required to raise the temperature of a given substance by 1°C.
• Applications:
  Because water can absorb a large amount of heat without its own temperature rising quickly, it is an excellent coolant.
  1. Vehicle Radiators: Water is used in radiators to absorb the excess heat from the engine.
  2. Regulating Body Temperature: The water in our bodies helps to maintain a stable internal temperature.

The Special Case of Ice (Anomalous Expansion)

• Normal Behavior: When most substances cool, their volume decreases.
• Water’s Behavior: When water cools and turns into ice, its volume increases.
• Density: Since Density = Mass / Volume, when the volume increases for the same mass, the density of ice decreases.
• Result: Because ice is less dense than water, a piece of ice floats on the surface of water.
• Importance for Aquatic Life:
  In cold countries, when lakes and rivers freeze, the ice (being less dense) forms on the top surface. This ice layer acts as a blanket, insulating the water below and preventing the entire lake from freezing solid. This allows fish and other aquatic life to survive in the liquid water underneath.
• Effect of Solutes on Boiling Point
  1. Observation: The boiling point of water with added substances (like salt) is higher than the boiling point of pure water (100°C).
  2. Reason: When salt is added, more energy is required to boil the water. This is known as boiling point elevation.

Structure and States of Water

• Molecular Structure: A water molecule is made up of two hydrogen atoms and one oxygen atom (H₂O).

• States: Water is a natural substance that can exist in all three states: solid (ice), liquid (water), and gas (steam).
• Liquid State Reason: A special kind of attractive force exists between water molecules. This force is responsible for surface tension and helps water keep its liquid form at room temperature, even though hydrogen and oxygen are gases.

A. Electrolysis

• Water can be split back into hydrogen and oxygen by a process called electrolysis.
• Using the Hoffman water voltameter

• hydrogen is produced at the negative Problems caused by Water Pollution: electrode and oxygen is produced at the positive electrode.

B. Density Anomaly (Unusual Property of Freezing)

• Maximum Density: The maximum density of water is at 4°C.
• Volume Change: When water is cooled or heated from 4C, its volume increases. When water turns into ice (cooled from 4°C to 0°C), its volume increases, and therefore its density decreases.
• Ice Floats: Since ice is less dense than liquid water, it floats on the surface.
• Survival of Aquatic Life: This floating layer of ice acts as an insulator, protecting the underlying water from freezing completely, allowing fish and other living things to survive in cold regions.

C. Effect of Dissolved Substances on Boiling Point

• The boiling point of water with added substances (like salt) is higher than that of pure water.
• This is because more energy is required to boil the water when a substance is added.

Water Pollution ((ജലമലീനീകരണം))
Water’s ability to dissolve many substances (as a universal solvent) also means it can easily become polluted.
Causes/Sources of Pollution:

• Chemicals from agricultural fields
• Chemicals from factories
• Oils from vehicles
• Improper waste disposal (dumping garbage, plastic)
• Sewage discharge

Problems Caused by Water Pollution:

• Destruction of aquatic plants
• Damage to the food chain
• Soil pollution
• Spread of water-borne diseases

Pure water is a basic human need, and millions suffer from diseases due to a lack of it, reinforcing the idea: “Right to water is a birthright”.

The comprehensive approach in SCERT Class 8 Basic Science Textbook Solutions Chapter 13 Acids, Bases, Salts Important Questions ensure conceptual clarity.

Acids, Bases, Salts Extra Questions and Answers Class 8 Basic Science Chapter 13 Kerala Syllabus

Acids, Bases, Salts Class 8 Important Questions

Question 1.
Which organic acid is responsible for the sour taste in tamarind?
a) Citric acid
b) Lactic acid
c) Acetic acid
d) Tartaric acid
Answer:
d) Tartaric acid

Question 2.
Which is the common component present in all acids that is responsible for their acidic properties?
a) Oxygen
b) Hydrogen
c) Chlorine
d) Sulphur
Answer:
(b) Hydrogen.

Question 3.
Substances that can increase the
concentration of hydroxide ions (OH^–) in an aqueous solution are called:
a) Acids
b) Salts
c) Alkalis
d) Non-metal oxides
Answer:
(c) Alkalis.

Question 4.
When an acid reacts with a highly reactive metal (like Zinc), it produces a gas. How is this gas identified?
a) It turns lime water milky.
b) It turns blue litmus red.
c) It puts out a burning matchstick with a ‘pop’ sound.
d) It forms a brown ring.
Answer:
(c) It puts out a burning matchstick with a ‘pop’ sound (This is the test for Hydrogen, H₂).

Question 5.
Statement 1: Acids have a sour taste and turn blue litmus red.
Statement 2: Bases have a bitter taste and turn red litmus blue.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
(a) Both statements are correct.

Question 6.
Statement 1: Metal oxides (like MgO) generally show basic properties.
Statement 2: Non-metal oxides (like CO₂) generally show acidic properties.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
(a) Both statements are correct.

Question 7.
Statement 1: A solution with a pH value of 3 is acidic.
Statement 2: A solution with a pH value of 9 is also acidic.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
(b) Only Statement 1 is correct. (Statement 2 is incorrect; pH > 7 is basic).

Question 8.
Classify the following substances as Acidic, Basic, or Neutral:
(Lemon juice, Soap solution. Water, Vinegar, Lime water)
Answer:
Acidic: Lemon juice, Vinegar.
Basic: Soap solution, Lime water (Calcium hydroxide).
Neutral: Water.

Question 9.
Match the food substance with the organic acid responsible for its sour taste.

Substance	Acid
1. Tamarind	a. Lactic acid
2. Vinegar	b. Citric acid
3. Yoghurt	c. Tartaric acid
4. Lemon juice	d. Acetic acid

Answer:
1 – c, 2 – d, 3 – a, 4 – b.

Substance	Acid
1. Tamarind	c. Tartaric acid
2. Vinegar	d. Acetic acid
3. Yoghurt	a. Lactic acid
4. Lemon juice	b. Citric acid

Question 10.
Find the acid and base that must be reacted to obtain the salt Sodium Sulphate (Na₂SO₄).
Answer:
Acid: Sulphuric acid (H₂SO₄)
Alkali/Base: Sodium hydroxide (NaOH)

Question 11.
Find and correct the error in this statement:
“Acids turn red litmus paper blue, and bases turn blue litmus paper red.”
Answer:
Error: The colors are swapped. Correction: Acids turn blue litmus paper red, and bases turn red litmus paper blue.

Question 12.
Find and correct the error in this statement:
“A pH value of 8 indicates an acidic solution.”
Answer:
Error: Acidic.
Correction: A pH value greater than 7 indicates a basic solution.

Question 13.
Find and correct the error in this statement:
“When acids react with carbonates (like marble), hydrogen gas is liberated.”
Answer:
Error: Hydrogen gas.
Correction: When acids react with carbonates, carbon dioxide gas (CO₂) is liberated.

Question 14.
Why does taking an antacid (like milk of magnesia) relieve indigestion or heartburn?
Answer:
Indigestion is often caused by excess hydrochloric acid (HCl) in the stomach. Antacids (like milk of magnesia, Mg(OH)₂) are bases. The base reacts with the excess acid in a neutralisation reaction, reducing the acidity and providing relief.

Question 15.
Why is soda water considered acidic?
Answer:
Soda water is made by dissolving carbon dioxide (CO₂) (a non-metal oxide) in water. The CO₂ reacts with the water (H₂O) to form carbonic acid (H₂CO₃), which gives soda water its acidic nature.

Question 16.
Why do farmers sometimes add slaked lime (calcium hydroxide) to agricultural soil?
Answer:
Farmers add slaked lime (a base) to reduce the acidity of acidic soil. This neutralisation reaction helps bring the soil pH to a level that is suitable for growing certain crops.

Question 17.
Complete the chemical equation for the dissociation of Sulphuric acid in water:
H₂SO₄ → ……………..+…………..
Answer:
H₂SO₄ → 2H⁺ + SO₄^2-.

Question 18.
Complete the chemical equation for the neutralisation reaction between dilute nitric acid and sodium hydroxide.
NaOH + HNO₃ → ……………..+…………..
Answer:
NaOH + HNO₃ → NaNO₃ + H₂O. (The products are a salt, Sodium Nitrate, and water).

Question 19.
A salt solution forms a white precipitate when Barium Chloride (BaCl₂) is added. This precipitate does not dissolve when dilute HCl is added. Which ion is present in the salt? (Sulphate ion or Carbonate ion?)
Answer:
The Sulphate ion (SO₄^2-). (Both ions form a white precipitate with BaCl₂, but only Barium Sulphate (BaSO₄) does not dissolve in HCl).

Question 20.
Describe the experiment to identify a carbonate salt.
Answer:
Take a little of the salt solution (e.g., sodium carbonate) in a test tube.
Add a few drops of dilute hydrochloric acid (HCl).
Observation 1: Bubbles (effervescence) will form, indicating a gas is liberated.
Confirmation: Pass this gas through clear lime water (Ca(OH)₂ solution) using a delivery tube.
Observation 2: The clear lime water will turn milky. This confirms the gas is Carbon Dioxide (CO₂) and the salt is a carbonate.

Question 21.
Describe the procedure to test if a salt (like KCl) contains the chloride ion (Cl ).
Answer:
Take a small amount of the salt solution (e.g., KCl) in a test tube.
Add a few drops of silver nitrate (AgNO₃) solution to it.
Observation: A white precipitate of silver chloride (AgCl) will be formed.

Question 22.
Describe the procedure to test if a salt (like Ammonium Sulphate) contains the sulphate ion (SO₄^2-).
Answer:
Take a small amount of the salt solution in a test tube and mix it with water. Add barium chloride (BaCl₂) solution to it.
Observation 1: A white precipitate (Barium Sulphate, BaSO₄ will form.
Confirmation: Add a few drops of dilute hydrochloric acid (HCl) to the precipitate.
Observation 2: The white precipitate will not dissolve.

Question 23.
Match the food substance in Column A with the acid it contains in Column B.

Column A	Column B
(i) Vinegar	(a) Lactic acid
(ii) Lemon juice	(b) Tartaric acid
(iii) Yoghurt	(c) Acetic acid
(iv) Tamarind	(d) Citric acid

Answer:
(i) – c, (ii) – d, (iii) – a, (iv) – b

Column A	Column B
(i) Vinegar	(c) Acetic acid
(ii) Lemon juice	(d) Citric acid
(iii) Yoghurt	(a) Lactic acid
(iv) Tamarind	(b) Tartaric acid

Question 24.
Match the common name in Column A with its chemical formula in Column B.

Column A	Column B
(i) Caustic soda	(a) Ca(OH)2
(ii) Milk of lime	(b) KOH
(iii) Caustic potash	(c) NaOH

Answer:
(i) – c, (ii) – a, (iii) – b

Column A	Column B
(i) Caustic soda	(c) NaOH
(ii) Milk of lime	(a) Ca(OH)2
(iii) Caustic potash	(b) KOH

Question 25.
Match the ion being tested with the correct observation.

Ion	Observation
(i) Chloride (Cl–)	(a) Bubbles of gas that turn lime water milky.
(ii) Sulphate (SO42-)	(b) A brown ring forms at the liquid junction.
(iii) Carbonate (CO32-)	(c) A white precipitate forms when silver nitrate is added.
(iv) Nitrate (NO3–)	(d) A white precipitate forms when barium chloride is added.

Answer:
(i) – c, (ii) – d, (iii) – a, (iv) – b

Ion	Observation
(i) Chloride (Cl–)	(d) A white precipitate forms when barium chloride is added.
(ii) Sulphate (SO42-)	(a) Bubbles of gas that turn lime water milky.
(iii) Carbonate (CO32-)	(b) A brown ring forms at the liquid junction.
(iv) Nitrate (NO3–)	(c) A white precipitate forms when silver nitrate is added.

Question 26.
Statement (i): Acids have a sour taste and turn red litmus blue.
Statement (ii): Bases have a bitter taste and turn blue litmus red.
a) Both statements (i) and (ii) are correct.
b) Statement (i) is correct, but statement (ii) is incorrect.
c) Statement (ii) is correct, but statement (i) is incorrect.
d) Both statements (i) and (ii) are incorrect.
Answer:
(d) Both statements are incorrect. (Acids turn blue to red, and bases turn red to blue).

Question 27.
Statement (i): The chemical reaction between an acid and a base to form salt and water is called neutralisation.
Statement (ii): A solution with a pH value of 7 is considered basic.
a) Both statements (i) and (ii) are correct.
b) Statement (i) is correct, but statement (ii) is incorrect.
c) Statement (ii) is correct, but statement (i) is incorrect.
d) Both statements (i) and (ii) are incorrect.
Answer:
(b) Statement (i) is correct, but statement (ii) is incorrect. (A pH of 7 is neutral).

Question 28.
Statement (i): Non-metal oxides (like CO₂) react with water to form substances that are generally acidic.
Statement (ii): Metal oxides (like MgO) react with water to form substances that are generally basic.
a) Both statements (i) and (ii) are correct.
b) Statement (i) is correct, but statement (ii) is incorrect.
c) Statement (ii) is correct, but statement (i) is incorrect.
d) Both statements (i) and (ii) are incorrect.
Answer:
(a) Both statements (i) and (ii) are correct.

Question 29.
What is the chemical definition of an acid, and what ion is the basis for all its general properties?
Answer:
Acids are substances that can increase the concentration of hydrogen ions (H⁺) in an aqueous solution. The H⁺ ion (or hydronium ion, H₃O⁺) is the basis for the general properties of acids.

Question 30.
Match the following appropriately.

Substances	Acid responsible for the sour taste
a. Lemon juice	i) Acetic acid
b.Yoghurt / Buttermilk	ii) Tartaric acid
c. Tamarind	iii) Citric acid
d.Vinegar	iv) Lactic acid

A. a – (ii) c – (iii), d – (iv) b – (i)
B. a – (i) (b) – (ii), c – (iii), d – (iv)
C. a – (iii), b – (ii) c – (iv) d – (i)
D. a – (iii), b – (iv), c – (ii) d – (i)
Answer:
D. a – (iii) b – (iv) c – (ii) d – (i)

Substances	Acid responsible for the sour taste
a. Lemon juice	iii) Citric acid
b.Yoghurt / Buttermilk	iv) Lactic acid
c. Tamarind	ii) Tartaric acid
d.Vinegar	i) Acetic acid

Question 31.
From the characteristics given below, find out those suitable for acids.
a) Turns blue litmus red
b) Soapy to touch
c) Have bitter taste
d) Have sour taste
(i) a, b
(ii) b, c
(iii) a, d
(iv) a, c
Answer:
(iii) a, d

Question 32.
Why are antacids, like Milk of Magnesia (magnesium hydroxide), used to treat indigestion?
Answer:
Indigestion is often caused by an excess of hydrochloric acid in the stomach. Antacids are basic substances.

They undergo a neutralisation reaction with the excess acid, reducing the acidity and providing relief.

Question 33.
Why does a farmer add slaked lime (calcium hydroxide) to soil that has a pH value of 5?
Answer:
A pH value of 5 is acidic (since it is less than 7). Slaked lime is a base. The farmer adds it to the soil to neutralize the excess acidity, making the soil suitable for growing crops.

Question 34.
Soda water is prepared by dissolving CO₂ gas under high pressure in water.
A. Which is the acid present in soda water? What is its chemical formula?
B. Write the chemical equation of the reaction.1
Answer:
A. Carbonic acid.
H₂CO₃
B. H₂O + CO₂ → H₂CO₃

Question 35.
Acid rain causes many environmental problems.
a) Explain how acid rain is formed.
b) Write any one environmental issue caused by acid rain.
Answer:
a) The gases like SO₂, NO₂ emitted from factories, motor vehicles thermoelectric power stations into air dissolve in rain water and cause acid rain.

b)

• Plants lose their ability to produce carbohydrate through photosynthesis as their leaves are destroyed.
• Severe acid rain destroys the greenery of a region.
• The acidic nature of water causes the death and distruction of fish and corals.

Question 36.
Calcium oxide reacts with water.
A. What is the product obtained by the reaction?
B. Property of which of the following it has?
(Acid, Alkali, Neutral solution)
Answer:
A. Calcium hydroxide (Ca(OH)₂)
B. Alkali

Question 37.
What are the situations in our day to day life in which neutralisation is made use of?
Answer:
In the agricultural field we use suitable manures according to the crops. The acid-alkaline properties are checked before applying the fertilizer. Similarly the acidic property is neutralised by adding alkaline substances like slaked lime. The acidity in our stomach is removed by treating with antacids. Antacids remove the acidity by neutralisation. In the laboratories in case of burning due to acids, weak alkalies are used as a first aid for its treatment. Here also neutralisation is made use of.

Question 38.
Describe the experiment to identify a carbonate salt.
Answer:
Take a little of the salt solution (e.g., sodium carbonate) in a test tube.
Add a few drops of dilute hydrochloric acid (HCl).
Observation 1: Bubbles (effervescence) will form, indicating a gas is liberated.
Confirmation: Pass this gas through clear lime water Ca(OH)₂ solution) using a delivery tube.
Observation 2: The clear lime water will turn milky. This confirms the gas is Carbon Dioxide (CO₂) and the salt is a carbonate.

Question 39.
Describe the experiment to identify a sulphate salt.
Answer:
Take a little of the salt solution in a test tube.
Add a few drops of barium chloride (BaCl₂) solution.
Observation 1: A white precipitate (Barium Sulphate, BaSO₄ will form.
Confirmation: Add a few drops of di-lute hydrochloric acid (HCl) to the precipitate.
Observation 2: The white precipitate will not dissolve.

Question 40.
The pH of solutions P, Q, Rare given.

Solution	PH
P	4
Q	9
R	7

A. Among them which is the neutral solution?
B. Among them which solution gives CO₂ when reacts with Na₂CO₃? Why?
C. Which solution has more concentration of OH^– ions?
Answer:
A. R
B. Solution P. Because it being an acid reacts with Na₂CO₃ and gives CO₂
C. Q

Question 41.
20mL of NaOH is taken in a conical flask and two drops of phenolphthalein are added. Then dilute HCl is added drop by drop, continuously shaking the beaker.
a) NaOH solution is turned into pink colour when phenolphthalein is added. Which nature of the solution is indicated here?
b) As HCl is added, the intensity of pink colour of solution decreases and finally disappeares. Why? Explain.
c) Write the chemical equation of the reaction that has occured here?
Answer:
a) Basic nature
b) Acidic HCl reacts with basic NaOH to form neutral salt and water. As the concentration of base decreas-es the pink colour fades and finally disappears due to neutralisation reaction.
c) NaOH + HCl → NaCl + H₂O

Question 42.
At the initial stages of cultivation the pH value o the soil is found. What is the need of it?
Answer:
In the case of farming, the pH value of the soil has an important role. A particular pH range is required for the healthy growth of certain crops. Certain crops grow well in the soil that is acidic in nature. But certain other crops grow well in the soil that is basic in nature. In situations like this, soil samples are collected in a suitable manner. The samples are mixed and water is added to get a solution. The pH value of the solution is found out to determine the pH value of the soil.

Question 43.
The pH of a soil is measured during soil testing.
a) Why the pH of soil is measured?
b) Suggest a method to increase the pH of soil with pH = 5.
Answer:
a) The pH of soil is an important factor for crops. It is important to identify whether the soil of a region is suitable for a particular crop. For some crops, soil with acidic nature is suitable and for some other crops, soil with alkaline nature is suitable.

b) Sprinkling of slaked lime.

Question 44.
A student adds a piece of magnesium ribbon to a test tube containing dilute sulphuric acid.
a) What is the main observation?
b) How can the gas produced be identified?
Answer:
a) The student will observe bubbles (effervescence) as the magnesium reacts with the acid,
b) The gas produced is hydrogen (H₂). It can be identified by holding a burning matchstick at the mouth of the test tube. The gas will extinguish the flame with a ‘pop’ sound.

Question 45.
Match the following appropriately.

Common name	Chemical name
a. Caustic soda	i) Magnesium hydroxide
b. Milk of lime	ii) Potassium hydroxide
c. Caustic Potash	iii) Sodium hydroxide
d. Milk of magnesia	iv) Calcium hydroxide

A. a – (ii), b – (i), c – (iii), d – (iv)
B. a – (i), b – (ii), c – (iii), d – (iv)
C. a – (iii), b – (ii), c – (iv), d – (i)
D. a – (iii), b – (iv), c – (ii) d – (i)
Answer:
D. a – (iii), b – (iv) c – (ii) d – (i)

Common name	Chemical name
a. Caustic soda	iii) Sodium hydroxide
b. Milk of lime	iv) Calcium hydroxide
c. Caustic Potash	ii) Potassium hydroxide
d. Milk of magnesia	i) Magnesium hydroxide

Question 46.
Complete the chemical equation for the reaction between magnesium and sulphuric acid.
Mg + H₂SO₄ → ……………. + …………..
Answer:
Mg + H₂SO₄ → MgS0₄ + H₂.

Question 47.
Complete the equation for the reac-tion when Carbon dioxide (CO₂) gas is passed through water. Name the product formed.
CO₂ + H₂O → ……………. + …………..
Answer:
CO₂ + H₂O → H₂CO₃ (Carbonic acid).

Question 48.
Complete the following neutralisation reaction and identify the salt formed.
KOH + HNO₃ → ……………. + …………..
Answer:
KOH + HNO₃ → KNO₃ + H₂O. The salt formed is Potassium Nitrate.

Question 49.
From the chapter, write the chemical formulas for the following acids:
(a) Sulphuric acid
(b) Phosphoric acid
(c) Nitric acid
Answer:
a) H₂SO₄
b) H₃PO₄
c) HNO₃

Question 50.
How many H⁺ (hydrogen) ions and SO₄^2- (sulphate) ions are liberated when 3 molecules of Sulphuric Acid (H₂SO₄) dissolve in water?
Answer:
One molecule of H₂SO₄ liberates 2H⁺ ions and SO₄^2- ion.
Therefore, 3 molecules will liberate:
3 \times 2 = 6H⁺ ions.
3 \times 1 = 3 SO₄^2- ions

Question 51.
Identify the chemical formulas of the acid and base needed to form the salt Aluminium Sulphate (Al₂(SO₄)₃).
Answer:
Acid: Sulphuric acid (H₂SO₄
Base: Aluminium hydroxide (Al(OH)₃)

Question 52.
What is the characteristic effect of an acid on blue litmus paper?
(A) Turns blue
(B) Turns red
(C) No change
(D) Turns yellow
Answer:
(B) Turns red

Question 53.
Which ion is primarily responsible for the general properties of acids in an aqueous solution?
(A) Cl^–
(B) OH^–
(C) H⁺
(D) Na⁺
Answer:
(C) H⁺

Question 54.
Which organic acid is responsible for the sour taste in Tamarind?
(A) Lactic acid
(B) Citric acid
(C) Acetic acid
(D) Tartaric acid
Answer:
(D) Tartaric acid

Question 55.
Which substance is commonly used as an Antacid to reduce excessive stomach acidity?
(A) Hydrochloric acid (HCl)
(B) Magnesium hydroxide (Mg(OH)₂)
(C) Sodium hydroxide (NaOH)
(D) Sulphuric acid (H₂SO₄)
Answer:
(B) Magnesium hydroxide (Mg(OH)₂)

Question 56.
Complete the following chemical reaction which shows an acid reacting with a highly reactive metal.
Zn + 2HCl → ZnCl₂ + ___________
Answer:
Zn + 2HCl → ZnCl₂ + H₂(Hydrogen gas (H₂) is liberated when acids react with highly reactive metals like Zinc.)

Question 57.
Define amphoteric oxides and give one example.
Answer:
Amphoteric oxides are oxides that have both acidic and basic properties. This means they can react with both acids and bases.
Example: Al₂O₃ (Aluminium oxide) or ZnO (Zinc oxide).

Question 58.
Write the balanced chemfcqi equation for the reaction of Sulphur dioxide (SO₂) gas with water (H₂O).
Answer:
SO₂ + H₂O → H₂SO₃ (Sulphurous acid)

Question 59.
What is the pH value of a neutral solution? What characteristics do solutions with a pH value greater than 7 show?
Answer:
The pH value of a neutral solution is 7. Solutions with a pH value greater than 7 show basic characteristics.

Question 60.
Explain what Acid Rain is, and state two negative effects it has on the environment.
Answer:
Acid Rain:
Acid rain is the result of nonmetal oxide gases like SO₂ (Sulphur dioxide) and NO₂ (Nitrogen dioxide) reaching the atmosphere, dissolving in rainwater, and falling to the earth as acids.

Two Environmental Effects:

1. It damages plant leaves, which reduces the ability of plants to produce starch through photosynthesis.
2. It increases the acidity of water sources, which in turn causes the death of aquatic life like fish and coral reefs.

Question 61.
Define Neutralisation Reaction and complete the chemical equation for the reaction between Sodium Hydroxide (NaOH) and Hydrochloric Acid (HCl).
NaOH + HCl → _________ + ______
Answer:
Neutralisation Reaction:
A neutralisation reaction is the chemical reaction in which an acid and a base react and lose their characteristic properties to form water and a salt.
Complete the equation:
NaOH + HCl → NaCl + H₂O
(The products are Sodium Chloride (NaCl), which is the salt, and Water (H₂O).)

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 13 Acids, Bases, Salts Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 13 Acids, Bases, Salts Question Answer Notes

Class 8 Basic Science Chapter 13 Notes Kerala Syllabus Acids, Bases, Salts Question Answer

Acids, Bases, Salts Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
Complete the table

Answer:

Substance	The colour change that occurs when exposed to moist red litmus	The colour change that occurs when exposed to moist blue litmus
Lemon juice	No Change	Turns Red
Lime water	Turns Blue	No Change
Sodium hydroxide	Turns Blue	No Change
Vinegar	No Change	Turns Red
Dilute hydrochloric acid	No Change	Turns Red

Question 2.
Find out which of the following statements is correct.
i. Nitrogen dioxide dissolves in water to form nitric acid.
ii. Phosphorus pentoxide (P₂O₅) is a nonmetal oxide.
iii. Sulphur trioxide turns moist red litmus blue.
Answer:
Statements (i) and (ii) are correct.

Question 3.
Explain any two cases where the importance of neutralisation reaction used in daily life.
Answer:
Neutralisation (Acid + Base → Salt + Water) is used to cancel out the effects of an acid with a base, or vice versa.

1. Treating Indigestion (Acidity): Our stomach produces hydrochloric acid HCl for digestion. If too much acid is produced, it causes acidity and discomfort. We take antacids (like Milk of Magnesia, Mg(OH)₂, which are basic medicines. The antacid (base) neutralizes the excess acid in the stomach, providing relief.

2. Controlling Soil pH: The pH of the soil is crucial for crop growth. If the soil is too acidic, farmers add a base (like slaked lime, Ca(OH)₂ to neutralize it. If the soil is too basic, farmers add an acidic substance (like ammonium sulphate) to neutralize it.

Question 4.
Solutions of some chemicals used in the laboratory are given in Box 1 below. Using these, write which salts given in Box 2 you can identify. Explain the method of experiment and observation.

Answer:
We can identify Ammonium carbonate and Ammonium chloride.
To identify Ammonium carbonate NH₄CO₃
Method: Take a sample of the salt solution. Add a few drops of Dilute HCl.
Observation: You will see bubbles (effervescence). If this gas is passed through lime water, it will turn milky.
Reason: Acids react with carbonates to produce carbon dioxide gas.
To identify Ammonium chloride (NH₄Cl): Method: Take a sample of the salt solution. Add a few drops of Silver nitrate solution.

Observation: A white precipitate (of Silver chloride, AgCl will form.
Reason: Silver nitrate is the test for the chloride ion Cl^–.

Question 5.
A bottle of salt in the lab had its label on it disintegrated. The details of the experiments conducted to identify the salt are given below.
• When a little barium chloride solution was added to the salt solution, a white precipitate formed.
• When dilute hydrochloric acid was added to the white precipitate, no observable change occurred.
Which salt is it? (Ammonium sulphate, Ammonium carbonate)
Answer:
Clues:
A white precipitate formed when Barium chloride BaCl₂ solution was added.
When dilute hydrochloric acid HCl was added to this precipitate, no observable change occurred.
Which salt is it? (Ammonium sulphate, Ammonium carbonate)

Reasoning:
Test 1 (Barium chloride): Both Ammonium sulphate NH₄SO₄ and Ammonium carbonate NH₄CO₃ would form a white precipitate with Barium chloride (BaCl₂).
NH₄SO₄ + BaCl₂ → BaSO₄ (white precipitate) + NH₄Cl
NH₄CO₃ + BaCl₂ → BaCO₃ (white precipitate) + NH₄Cl

Test 2 (Dilute HCl): This is the deciding test.
The precipitate did not change when HCl was added. This is a property of Barium sulphate BaSO₄.
If the precipitate had been Barium carbonate BaCO₃, it would have reacted with the HCl (acid + carbonate) and dissolved. Answer: The salt is Ammonium sulphate.

Question 6.
A colourless acid solution is in a bottle in the laboratory. 5 mL of it is taken in a test tube. 2 mL of dilute hydrochloric acid is added to it, no observable changes occur. After taking 5 ml. of the solution in another test tube, when 2 mL of silver nitrate solution is added, a white precipitate is formed.
i) Which acid is the solution in the bottle? When NaOH solution is added dropwise to 5 mL of the solution, it is observed that the pH gradually increases.
ii) When the pH reaches 7, what are the possible compounds present in the solution?
iii) Write the chemical equation for the reaction between NaOH and the acid solution.
Answer:
Test 1: Solution + dilute HCl → No observable change.
Test 2: Solution + Silver nitrate → A white precipitate is formed.
Test 3: When NaOH (base) is added, the pH gradually increases (this confirms the initial solution is an acid).
i) Test 2 (Silver nitrate) gives a white precipitate. This is the positive test for the Chloride ion Cl^–.
Since the solution is an acid and it contains Cl^– ions, the acid must be Hydrochloric acid (HCl).
(Test 1 confirms it’s not a carbonate solution, which we already know since it’s an acid).

ii) When pH = 7, the solution is neutral. This is the exact point of neutralisation.
The reaction is: HCl (acid) + NaOH (base) → NaCl (salt) + H₂O (water).
Answer:
The compounds present are Sodium chloride (NaCl) and Water (H₂O).

iii) Write the chemical equation for the reaction between NaOH and the acid solution.
Answer:
NaOH + HCl → NaCl + H₂O

Basic Science Class 8 Chapter 13 Question Answer Kerala Syllabus

Textbook Page No : 219 & 220

Question 1.
What taste do they have in common?
Answer:
They are all sour in taste.

Question 2.
What could be the reason?
Answer:
The sour taste is due to the presence of acids, which are substances that produce hydrogen ions (H⁺) in aqueous solution.

Question 3.
What colour changes occur when red litmus paper and blue litmus paper are used to test these food items?
Answer:
Acids turn blue litmus paper red. Red litmus paper will show no change.

Question 4.
Conduct an experiment to note the colour change to litmus paper with hydrochloric acid, sulphuric acid and nitric acid…
Answer:
Observation: All three strong acids will turn blue litmus paper red.

Question 5.
Reaction of Zinc with dilute Hydrochloric acid (Observation and Reason):
Answer:
Observation: A pop sound will be heard when a burning matchstick is brought near the test tube.
Reason: This observation confirms the production of hydrogen gas (H₂), which is liberated when highly reactive metals (like zinc and magnesium) react with acids.

Question 6.
Reaction with Carbonates (Observation when gas is passed through clear lime water):

Answer:
Observation: The clear lime water turns milky (or cloudy).

Question 7.
Complete the table given below (Table 13.1):

Answer:

Metal	Acid	Chemical equation
Zinc	Hydrochloric acid	Zn + 2HCl → ZnCl2 + H2
Zinc	Sulphuric acid	Zn + H2SO4 → ZnSO4 +H2
Magnesium	Hydrochloric acid	Mg + 2HCl → MgCl2 + H2
Magnesium	Sulphuric acid	Mg + H2SO2 → MgSO2 + H2

Textbook Page No : 221 & 222

Question 8.
Which gas is released through the delivery tube?
Answer:
Carbon dioxide gas (CO₂).

Question 9.
What is the symbol for hydrogen?
Answer:
H.

Question 10.
What is the chemical formula of hydrochloric acid?
Answer:
HCl.

Question 11.
Which are the ions formed when nitric acid dissolves in water?
Answer:
H⁺ (hydrogen ion) and NO₃^– (nitrateion).

Question 12.
Complete the table given below (Table 13.2):

Answer:

Name of acid	Chemical formula	Ions liberated when dissolved in water
Hydrochloric acid	HCl	H+, Cl–
Sulphuric acid	H2SO4	2H+, SO42-
Carbonic acid	H2CO3	2H+, CO32-
Phosphoric acid	H3PO4	3H+, PO43-

Question 13.
Which is the gas liberated when a soda bottle is opened?
Answer:
Carbon dioxide gas (CO₂).

Question 14.
Is soda water acidic or basic?
Answer:
Soda water is acidic.

Question 15.
Which is the acid in soda water?
Answer:
Carbonic acid.

Question 16.
Write the chemical formula of the acid in soda water.
Answer:
H₂CO₃.

Question 17.
Complete the chemical equation for the reaction of sulphur dioxide (SO₂) gas in water to form acid:
Answer:
SO₂ + H₂O → H₂SO₃ (sulphurous acid).

Textbook Page No : 223

Question 18.
Write the chemical formula and chemical name of the acids formed when the oxides given in the table react with water (Table 13.5):

Answer:

Main oxide of the element	Chemical formula of the acid formed by reacting with water	Chemical name of the acid formed by reacting with water
Nitrogen dioxide (NO2)	HNO3	Nitric acid
Phosphorus pentoxide (P2O5)	H3PO4	Phosphoric acid
Sulphur trioxide (SO3)	H2SO4	Sulphuric acid

Textbook Page No : 224 & 225

Question 19.
List the General properties of bases:
Answer:

1. Turns red litmus blue.
2. Has a bitter taste.
3. Feels soapy or slippery to the touch.

Question 20.
White powder obtained after burning magnesium ribbon:
Answer:
The white powder is Magnesium oxide (MgO).

Question 21.
Nature of the product when MgO is added to water:
Answer:
The product is Magnesium hydroxide (Mg(OH)₂). It is basic and will turn red litmus paper blue.

Question 22.
Complete the chemical equation of the reaction of quicklime (CaO) with water:
Answer:
CaO + H₂O → Ca(OH)₂ (Calcium hydroxide).

Question 23.
Are CaO and MgO, metal oxides or nonmetal oxides?
Answer:
They are metal oxides. (Metal oxides generally show basic properties).

Question 24.
Complete the ionisation equation for calcium hydroxide:
Answer:
Ca(OH)₂ → Ca²⁺ + 2OH^–

Question 25.
What is the common ion liberated when alkalies dissolve in water?
Answer:
The common ion is the hydroxide ion (OH^–).

Textbook Page No : 226 & 227

Question 26.
Which was the colour of NaOH solution when phenolphthalein was added?
Answer:
The solution turned pink or magenta.

Question 27.
What property of NaOH solution does this indicate?
Answer:
It indicates that the solution is basic.

Question 28.
Will NaOH remain in the conical flask when the colour completely disappears?
Answer:
No. The disappearance of color (endpoint) means the acid has neutralized the base, leaving mostly salt and water.

Question 29.
What is the pH value of a neutral solution?
Answer:
The pH value of a neutral solution is 7.

Question 30.
What characteristics do solutions with a pH value greater than 7 show?
Answer:
They are basic.

Question 31.
What characteristics do solutions with a pH value less than 7 show?
Answer:
They are acidic.

Textbook Page No : 228 & 229

Question 32.
Complete Table 13.7 (using typical nature):

Answer:

Name of substance	pH value (Typical)	Acidic/Basic/Neutral
Lemon juice	< 7	Acidic
Dilute Hydrochloric acid	< 7	Acidic
Water	≈ 7	Neutral
Common salt solution	≈ 7	Neutral
Sodium hydroxide solution	> 7	Basic
Soap solution	> 7	Basic

Question 33.
As the pH value increases, does it become more acidic or more basic?
Answer:
It becomes more basic.

Question 34.
What are the products formed when sodium hydroxide and dilute hydrochloric acid react?
Answer:
Sodium chloride (NaCl) (a salt) and water (H₂O).

Question 35.
What is the product formed when the common component of the acid (H⁺) and the common component of the alkali (OH^–) combine?
Answer:
Water (H₂O).

Question 36.
What is the product formed when the positive ion in sodium hydroxide (Na⁺) and the negative ion in hydrochloric acid (Cl^–) combine?
Answer:
The salt Sodium chloride (NaCl).

Question 37.
Complete the chemical equation for the reaction between dilute sulphuric acid and magnesium hydroxide solution:
Answer:
Mg(OH)₂ + H₂SO₄ → MgSO₄ + 2H₂O

Question 38.
What is the salt formed?
Answer:
Magnesium sulphate (MgSO₄).

Question 39.
Find and write the acid and alkali/base that must be reacted to obtain the salts:

Answer:

Salt	Chemical Formula	Acid	Alkali/Base
Calcium sulphate	CaSO4	H2SO4 (Sulphuric acid)	Ca(OH)2 (Calcium hydroxide)
Aluminium sulphate	Al2(SO4)3	H2SO4 (Sulphuric acid)	Al(OH)3 (Aluminium hydroxide)
Barium nitrate	Ba(NO3)2	HNO3 (Nitric acid)	Ba(OH)2 (Barium hydroxide)

Textbook Page No : 230

Question 40.
What are the products formed when sodium hydroxide and dilute nitric acid react?
Answer:
NaOH + HNO₃ → NaNO₃ + H₂O

Question 41.
What is the salt formed here?
Answer:
Sodium nitrate (NaNO₃).

Question 42.
Identifying Nitrate Salts (Brown Ring Test)
Answer:
The experiment involves mixing a nitrate salt solution (like Ammonium nitrate) with freshly prepared ferrous sulphate solution and then carefully adding concentrated sulphuric acid.
Observation: A distinct brown ring will form at the junction of the two liquid layers (the aqueous solution and the concentrated sulphuric acid).

Question 43.
Identifying Carbonate Salts
Answer:
The experiment involves reacting a carbonate salt solution (like Sodium carbonate) with an acid (Dilute Hydrochloric Acid) and passing the resultant gas through clear lime water.
Observation: The clear lime water will turn milky (or cloudy). This observation confirms that the gas released is carbon dioxide (CO₂), which is characteristic of the reaction between an acid and a carbonate salt.

Class 8 Basic Science Chapter 13 Question Answer Extended Activities

Question 1.
Collect soil from different parts around your house. Mix it with some water and stir it well. After some time, collect the clear water and find its pH value using pH solution, pH paper or pH meter. Similarly, find the pH of water from different sources and display it on a chart.

Question 2.
Collect information from farmers about the methods they use to increase or decrease the acidity of the soil while preparing the soil suitable for different crops in your area and prepare a report.

Acids, Bases, Salts Class 8 Notes

Class 8 Basic Science Acids, Bases, Salts Notes Kerala Syllabus
Acid

• Acids are substances that can increase the concentration of hydrogen ions (H⁺) in an aqueous solution (in
• water).
  Properties: Acids have a sour taste and turn blue litmus paper red.
• Common Component: The common component in all acids is Hydrogen (H). which is liberated as H+ ions (or hydronium ions, H₃O⁺) in water. These ions are the basis for all acidic properties.
• Acids have several key chemical properties that can be used to identify them.
  1. Taste: They have a sour taste. (Note: It is dangerous to taste chemicals in a lab).
  2. Litmus Test: Acids turn blue litmus paper red.
  3. Reaction with Reactive Metals: Acids react with highly reactive metals (like Zinc and Magnesium) to liberate Hydrogen gas (H₂).
  4. Reaction with Carbonates: Acids react with carbonates (like calcium carbonate/marble) to liberate Carbon Dioxide gas (CO₂).

ആസിഡുകൾക്ക് പ്രധാനമായും 4 സ്വഭാവങ്ങ ളുണ്ട്

• പുളി രുചി.
• നീല ലിറ്റ്മസിനെ ചുവപ്പ് ആക്കുന്നു.
• സിങ്ക് (Zinc), മഗ്നീഷ്യം (Magnesium) തുട ങ്ങിയ ക്രിയാശീലമുള്ള ലോഹങ്ങളുമായി പ വർത്തിച്ച് ഹൈഡ്രജൻ (H₂) വാതകം ഉണ്ടാ ക്കുന്നു.
• കാർബണേറ്റുകളുമായി (ഉദാഹരണത്തിന്, മാ ർബിൾ) പ്രവർത്തിച്ച് കാർബൺ ഡൈ ഓക് സൈഡ് (CO₂) വാതകം ഉണ്ടാക്കുന്നു.

Organic Acids: These are generally weaker acids found in food.

• Lemon: Citric acid
• Yoghurt/Curd: Lactic acid
• Tamarind: Tartaric acid
• Vinegar: Acetic acid

Mineral Acids : These are stronger acids typically prepared in a lab from minerals (e.g., Hydrochloric acid, Sulphuric acid).

Common Acids

Name of Acid	Chemical Formula	Used/Found In
Hydrochloric Acid	HCl	Gastric juice, industrial cleaning
Sulphuric Acid	H2SO4	Batteries, fertilizers, King of Chemicals
Carbonic Acid	H2CO3	Soda water, soft drinks
Acetic Acid	CH3COOH	Vinegar (food preservative)

Acid Reactions
1. With Reactive Metals: Acids react with metals like Zinc (Zn) and Magnesium (Mg) to liberate Hydrogen gas (H₂).
Mg + HCl → MgCl₂ + H₂

2. With Carbonates: Acids react with car-bonates (like marble, CaCO₃) to liberate Carbon Dioxide gas (CO₂).
Test for CO₂: It turns clear lime water milky.

3. With Non-metal Oxides: Non-metal oxides (like CO₂, SO₂) dissolve in water to form acids.
CO₂ + H₂O → H₂CO₃ (Carbonic acid)

Substance Acidic

• The general properties of all acids (like sour taste, turning blue litmus red, and reacting with metals) are because of a common component.
• The Common Component: Hydrogen (H) is the common component in all acids.
• Acids are substances that can increase the concentration of hydrogen ions (H⁺) in an aqueous solution (in water).
• Hydronium Ions (H₃O⁺): These liberated H⁺ ions are highly reactive and combine with water (H₂O) molecules to form hydronium ions (H₃O⁺).
  H⁺ + H₂O → H₃O⁺

എല്ലാ ആസിഡുകളിലും പൊതുവായി അടങ്ങിയി രിക്കുന്ന ഘടകമാണ് ഹൈഡ്രജൻ (H). ആസിഡു കൾ ജലത്തിൽ ലയിക്കുമ്പോൾ (aqueous solu tion) ഹൈഡ്രജൻ അയോണുകൾ (H⁺) സ്വതന്ത്ര മാക്കുന്നു. ഈ H⁺ അയോണുകളാണ് ആസിഡു കളുടെ എല്ലാ പൊതു സ്വഭാവങ്ങൾക്കും കാരണം.

Acids from Non-metal Oxides
A major category of acids is formed when non-metal oxides (oxides of elements like Carbon, Sulphur, Nitrogen) react with water.

• General Rule: The substances formed when nonmetal oxides react with water generally show acidic properties.
• Formula: Non-metal Oxide + Water → Acid

അലോഹ ഓക്സൈഡുകൾ (Non-metal oxides) ജലവുമായി (Water) പ്രവർത്തിക്കുമ്പോൾ ആസിഡുകൾ ഉണ്ടാകുന്നു. അതുകൊണ്ട് അലോ ഹ ഓക്സൈഡുകളെ ‘ആസിഡ് അൻഹൈ ഡ ഡുകൾ’ എന്നും വിളിക്കാറുണ്ട്.

Examples:
1. Soda Water:

• The gas liberated when a soda bottle is opened is Carbon dioxide (CO₂).
• This CO₂ (a nonmetal oxide) reacts with water (H₂O) to form Carbonic acid (H₂CO₃), which makes soda water acidic.
• CO₂ + H₂O → H₂CO₃ (Carbonic acid)

2. Sulphur Dioxide:
• SO₂ + H₂O → H₂SO₃ (Sulphurous acid)

Acid Rain
Acid rain refers to any precipitation (rain, snow, fog, etc.) that has a pH below 5.6, making it significantly more acidic than normal rainwater.

Formation
Acid rain is primarily caused by two major air pollutants released from human activities, mainly the burning of fossil fuels (coal and petroleum) in industries and vehicles:

1. Sulphur Dioxide (SO₂): Released mainly from power plants. This gas dissolves in atmospheric water to form Sulphuric Acid (H₂SO₄).
2. Nitrogen Oxides (NO₂): Released mainly from vehicles. These gases dissolve in atmospheric water to form Nitric Acid (HNO₃).

These strong mineral acids then fall to the Earth as acid rain.

Effects
Acid rain has severe detrimental effects:

• Corrosion: It accelerates the corrosion of metal structures and the deterioration of stone buildings and monuments (like marble, which is calcium carbonate), leading to “stone cancer.”
• Aquatic Life: It lowers the pH of lakes and rivers, making the water toxic and threatening the survival of fish and other aquatic organisms.
• Vegetation/Soil: It damages leaves and increases the acidity of the soil, leaching essential nutrients and hindering the growth of crops and forests.

Bases (ബേസുകൾ)
Just as we studied acids, let’s look at the properties of bases.

General properties of bases:

• They have a bitter taste and feel soapy to the touch.
• Bases turn red litmus paper blue.
• Source: Metal oxides (ലോഹ ഓക്സൈഡുകൾ) (e.g., Magnesium oxide MgO, Calcium oxide CaO) generally show basic properties.
• Metal Oxide + Water → Base
  MgO + H₂O → Mg(OH)₂ (Magnesium hydroxide)

ആസിഡുകൾ അലോഹ ഓക്സൈഡുകൾ (nonmetal oxides) ജലത്തിൽ ലയിക്കുമ്പോൾ ഉണ്ടാ കുന്നതുപോലെ, ലോഹ ഓക്സൈഡുകൾ (metal oxides) ജലത്തിൽ ലയിക്കുമ്പോഴാണ് ബേസു കൾ ഉണ്ടാകുന്നത്. ഉദാഹരണത്തിന്, മഗ്നീഷ്യം ഓക്സൈഡ് അല്ലെങ്കിൽ കാൽസ്യം ഓക്സൈഡ്.

Alkalis

• Alkalis are bases that dissolve in water. (Not all bases dissolve in water).
• (Chemical): Alkalis are substances that can increase the concentration of hydroxide ions (OH^–) in an aqueous solution.
• The hydroxide ion (OH^–) is the common ion liberated by all alkalis when dissolved in water. This ion is responsible for all the general properties of bases.

Dissociation of Alkalis:
NaOH → Na⁺ + OH^– (hydroxide ion)
Ca(OH)² → Ca²⁺ + 2OH^–
ആസിഡുകളുടെ പൊതുസ്വഭാവത്തിന് കാരണം H⁺ അയോണുകൾ ആയതുപോലെ, ബേസുകളുടെ പൊതുസ്വഭാവത്തിന് കാരണം ഹൈഡ്രോക്സൈ ഡ് അയോണുകൾ (OH^–) ആണ്. ജലത്തിൽ ലയി ക്കുമ്പോൾ OH^– അയോണുകൾ സ്വതന്ത്രമാക്കാൻ കഴിയുന്ന ബേസുകളെയാണ് ക്ഷാരങ്ങൾ (Alkalis) എന്ന് വിളിക്കുന്നത്.

Common name	Chemical name	Chemical formula
Caustic soda	Sodium hydroxide	NaOH
Milk of lime	Calcium hydroxide	Ca(OH)2
Caustic potash	Potassium hydroxide	KOH

Neutralisation Reaction
The chemical reaction in which an acid and a base react and lose their properties to form water and a salt is known as neutralisation reaction. The common H⁺ ions from the acid and OH^– ions from the base combine to form H₂O.
Acid + Base → Salt + Water

• Example: NaOH + HCl → NaCl +H₂O
  (Sodium Hydroxide + Hydrochloric Acid → Sodium Chloride + Water)
• Indicator Use: Phenolphthalein is an indicator used in neutralisation. It is pink in a basic solution and turns colourless when the solution becomes neutral or acidic.
• Example (Antacid): Taking a basic antacid (like Mg(OH)₂, Milk of Magnesia) to neutralize excess stomach acid (HCl).
• Example (Soil): Adding slaked lime (base) to reduce soil acidity.

ആസിഡും ബേസും തമ്മിൽ പ്രവർത്തിച്ച് അവ യുടെ ഗുണങ്ങൾ പരസ്പരം ഇല്ലാതാവുകയും, തത്ഫലമായി ലവണവും (Salt) ജലവും (Water) ഉണ്ടാകുകയും ചെയ്യുന്ന പ്രവർത്തനമാണ് നിർവീ രീകരണം (Neturalisation).

pH Value

• To measure the “degree” of acidic or basic nature of a substance, we use the pH scale.
• The pH scale is used to determine the degree of acidic or basic nature of a substance. It was developed by the Danish scientist Sorensen and is based on the concentration of H⁺ ions in the solution.

• The Scale (Fig 13.4): The scale ranges from 1 to 14.
  • pH value less than 7 (< 7): The solution is Acidic (ആസിഡ് സ്വഭാവം).
  • pH value of 7: The solution is Neutral (നിർവീരും).
  • pH value greater than 7 (> 7): The solution is Basic (ബേസിക് സ്വഭാവം).
• Measurement: We can measure pH using pH paper, pH solution, or a pH meter.
• Trend: As the pH value increases, the substance becomes more basic (and less acidic).

ഒരു പദാർത്ഥം ആസിഡ് ആണോ ബേസ് ആണോ എന്നും, അതിന്റെ ശക്തി എത്രത്തോളമുണ്ടെന്നും അളക്കാനുള്ള ഒരു സ്കെയിൽ ആണ് pH കയിൽ. ഇത് 1 മുതൽ 14 വരെയാണ്.

Application: pH in Soil (മണ്ണിലെ pH)
The pH of the soil is a critical factor for the proper growth of crops.

• To reduce acidity (if soil is too acidic):
  A base like slaked lime (Calcium hydroxide) is added.
• To reduce basicity (if soil is too basic):
  An acidic substance like ammonium sulphate or aluminium sulphate is added.

Salts

• Salts are ionic compounds formed by the reaction of an acid and a base (neutralisation reaction).
• Formation:
  1. The common component of the acid (H⁺) and the common component of the base (OH^–) combine to form Water (H₂O).
  2. The positive ion from the base (e.g., Na+ from NaOH) combines with the negative ion from the acid (e.g., Cl^– from HCl) to form the Salt.

ഒരു ആസിഡും ബേസും തമ്മിൽ പ്രവർത്തിക്കു മ്പോൾ (neturalisation), ആസിഡിലെ H⁺ അയോ ണും ബേസിലെ OH^– അയോണും ചേർന്ന് ജലം (Water) ഉണ്ടാകുന്നു. ബാക്കിയുള്ള, ബേസിലെ പോസിറ്റീവ് അയോണും ആസിഡിലെ നെഗറ്റീവ് അയോണും ചേർന്ന് ഉണ്ടാകുന്ന പദാർത്ഥമാണ് ലവണം (Salt).

Examples of Salt Formation:

• HCl (acid) + NaOH (base) → NaCl(salt) + H₂O (water)
• H₂SO₄ (acid) + Mg(OH)₂ (base) → MgSO₄ (salt) + H₂O (water)
• HNO₃ (acid) + NaOH (base) → NaNO₃(salt) + H₂O(water)

Identification of Ions in Salts (അയോണുകളെ തിരിച്ചറിയൽ)
We can use chemical tests to identify the negative ions present in a salt.

• Test for Chloride (Cl^–) ion:
  Reagent: Add Silver Nitrate (AgNO₃) solution.
  Observation: A white precipitate (വെളുത്ത അവക്ഷിപ്തം)) of Silver Chloride (AgCl) is formed.
• Test for Sulphate (SO₄^2-) ion:
  Reagent: Add Barium Chloride (BaCl₂) solution.
  Observation: A white precipitate of Barium Sulphate (BaSO₄) is formed. Confirmation: This precipitate does not dissolve when dilute HCl is added to it.
• Test for Nitrate (NO₃^–) ion (Brown Ring Test):
  Reagent: Add freshly prepared Ferrous Sulphate (FeSO₄) solution, and then add concentrated Sulphuric Acid (H₂SO₄) slowly down the sides of the test tube.
  Observation: A brown ring forms at the junction where the two liquids meet.

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 12 Spherical Mirrors Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 12 Spherical Mirrors Question Answer Notes

Class 8 Basic Science Chapter 12 Notes Kerala Syllabus Spherical Mirrors Question Answer

Spherical Mirrors Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
A concave mirror has a focal length of 30 cm. Find out its radius of curvature.
Answer:
Given: Focal length (f) = 30 cm
Formula: The focal length (f) is half of the radius of curvature (R).
f = R/2 Calculation:
R = 2f
R = 2 × 30 cm
R = 60 cm
The radius of curvature is 60 cm.

Question 2.
OA is a ray incident obliquely on a concave mirror. Draw and mark the path of its reflected ray. Write on what basis you marked this like.

Answer:
The Law of Reflection.

• In this case, the light ray (OA) is striking the pole (P) of the mirror.
• At the pole, the principal axis itself acts as the normal (the 90° line).
• According to the law of reflection, the angle of incidence (i) must be equal to the angle of reflection (r). Therefore, the reflected ray will travel down wards at the same angle to the principal axis as the incident ray.

Question 3.
Write what type of spherical mirrors should be used to obtain images with the following characteristics:
a. Real, smaller than the object
b. Virtual, smaller than the object
c. Real, larger than the object
d. Virtual, larger than the object
Answer:
a. Concave Mirror.
Reason: This happens when the object is placed beyond C or at infinity.)

b. Convex Mirror.
Reason: A convex mirror always forms a virtual, erect, and small image, regardless of the object’s position.)

c. Concave Mirror.
Reason: This happens when the object is placed between C and F.)

d. Concave Mirror.
Reason: This is the special case used for makeup or shaving mirrors, where the object is placed between F and P.)

Question 4.
Observe the picture.

a) If the object shown in the picture is replaced with an object of 6 cm height at the same position, what will be the height of the image?
b) If the distance of the object from the mirror was 30 cm and an image of the same size as the object was obtained on the screen, what is the focal length of the mirror?
Answer:
a. m = \(\frac{h_1}{h_0}\) = \(\frac{6 \mathrm{~cm}}{3 \mathrm{~cm}}\) = -2
m = \(\frac{h_1}{h_0}\)
h₁ = m × h₀
= -2 × 6
= -12 cm

b. If image is same size that of object. The object will be at C
∴ object distance = 30
R = 30 cm
f = \(\frac{R}{2}\) = \(\frac{30}{2}\) = 15 cm

Basic Science Class 8 Chapter 12 Question Answer Kerala Syllabus

Textbook Page No : 203

Question 1.
What is special about the mirror in his hand (Fig. 12.1)?
Answer:
The mirror is a concave mirror (a type of spherical mirror). It is special be-cause it makes the person’s reflection (image) appear slightly larger than the object.

Question 2.
Can you see your face in it (The flat, silver paper on cardboard)?
Answer:
Yes, you can see your face. An image is formed when light reflects off a smooth surface like the silver paper.

Textbook Page No : 204 & 205

Question 3.
What change do you notice in the image when you bend the cardboard inward?

Answer:
When bent inward (acting as a concave mirror), the image changes and can become inverted, or larger and erect if held very close.

Question 4.
What if you bend it outward?
Answer:
When bent outward (acting as a convex mirror), the image will appear erect and smaller (diminished).

Question 5.
Complete Table 12.1: Characteristics of the image

Answer:

Shape of the sheet	Characteristics of the image
Flat (Plane Mirror)	Erect, Same size as the object, Virtual.
Bend outward (Convex Mirror)	Erect, Smaller than the object, Virtual.
Bend inward (Concave Mirror – close range)	Erect, Larger (Magnified) than the object, Virtual.

Question 6.
How does the image appear on the outer side of the spoon?
Answer:
The outer side acts as a convex mirror, forming an image that is Erect, Virtual, and Smaller.

Question 7.
What about the inner side?
Answer:
The inner side acts as a concave mirror. If you hold it close, the image is Erect, Virtual, and Larger. If you hold it further away, the image is Inverted, Real, and Smaller.

Question 8.
How the images formed on curved surfaces differ from those formed by plane mirrors.
Answer:

• Plane Mirrors: form an image that is always erect, virtual, and the same size.
• Curved Surfaces (Spherical Mirrors) can form images that are real or virtual, inverted or erect, and smaller, the same size, or larger than the object.

Question 9.
Do the reflected rays converge at a point (Ice Cream Ball-Inner Surface/ Concave Mirror)?
Answer:
Yes, the reflected rays converge to a single point called the principal focus.

Question 10.
What difference do you observe now (Ice Cream Ball-Outer Surface/Convex Mirror)?
Answer:
The reflected rays diverge (spread out) and do not meet. They appear to come from a point behind the mirror.

Textbook Page No : 206

Question 11.
Complete Table 12.2 (Law of Reflection in Spherical Mirrors)

Answer:
In spherical mirrors, the angle of incidence (i) is equal to the angle of reflection (r).

SI No	Angle of incidence (i) (Degree)	Angle of reflection (r) (Degree)
1	30	30
2	40	40
3	60	60

Textbook Page No : 208

Question 12.
The principal focus of a convex mirror is virtual. Why?
Answer:
The principal focus is virtual because the light rays that fall parallel to the principal axis do not actually meet after reflection; they only appear to diverge from a point behind the mirror. Since the rays do not converge at this point, the image or focus cannot be caught on a screen.

Question 13.
What would be the radius of curvature of a concave mirror with a focal length of 40 cm?
Answer:
The relationship is: R = 2f (Radius of curvature is twice the focal length)
R = 2 × 40 cm
R = 80 cm

Question 14.
What are the characteristics of the images formed by plane mirrors?
Answer:
The characteristics are: Erect and Virtual. The image is also the same size as the object.

Textbook Page No : 209

Question 15.
Write down the characteristics of the image of a distant object formed on the wall with a concave mirror.
Answer:
The image is formed at the principal focus (F). The characteristics are:

• Smaller than the object (Highly diminished)
• Inverted
• Real

Question 16.
At what position is the screen placed to get a clear image?

Answer:
For a Convex Mirror, a clear, real image can never be obtained on a screen because a convex mirror always forms a virtual image behind the mirror.

Question 17.
What are the characteristics of the image?
Answer:
When a concave mirror is used to form the image of a distant object (like the sun or a far-off tree), and the screen is placed at the Principal Focus (F).

1. Nature: Real (can be formed on a
2. Orientation: Inverted (upside down), as a tiny, bright point).
3. Size: Highly Diminished (much, much smaller than the object—it appears as a tiny, bright point).
4. Position: At the Principal Focus (F). them.

Textbook Page No : 210

Question 18.
Complete Table 12.3: Concave Mirror Image Formation.

Answer:

SI No	Position of the object	Position of the image	Characteristics of the image
1	Very far (at infinity)	At F (Principal Focus)	Small, Inverted, Real
2	Beyond C (Centre of Curvature)	Between F and C	Small (Diminished), Inverted, Real
3	At C	At C	Same size, Inverted, Real
4	Between C and F	Beyond C	Large (Magnified), Inverted, Real
5	At F	At infinity	Highly magnified. Inverted, Real
6	Between F and P (Pole)	Behind the mirror	Large (Magnified), Erect, Virtual

Question 19.
Could the analysis of this table provide the answer to the question related to the introduction picture of this unit?
Answer:
Yes. The mirror in the introduction makes the face appear slightly larger. This corresponds to the case in SI No. 6 (Object Between F and P), which is a characteristic of a concave mirror.

Question 20.
What are the characteristics of the mirror that reflects your face at a spectacle shop? Why does the face appear larger?
Answer:
It is a Concave Mirror.
Reason: Based on Table 12.3 (Row 6), a concave mirror ¡s the only mirror that can produce a large, erect, and virtual image.
This happens when the object (the face) is placed very close to the mirror, “Between F and P”. This is often used as a shaving mirror or makeup mirror.

Question 21.
Are the same types of images formed in a convex mirror?
Answer:
No. Concave mirrors form both real and virtual images, while a convex mirror forms only one type of image.

Question 22.
Can you see the image?
Answer:
Yes, you can see the image by looking into the mirror.

Question 23.
Can you project it on a screen?
Answer:
No. The image formed is Virtual, meaning it cannot be caught on a screen.

Question 24.
Characteristics of the Image Formed (Complete the list):
Answer:
A convex mirror always forms an image that is:

• Erect
• Small (Diminished)
• virtual
• Always between the principal focus (F) and the pole (P)

Textbook Page No : 211 & 213

Textbook Page No : 213 & 214

Complete the image formation for the remaining positions:

• Object is Beyond C:

Position of the image: Between C and F (C യ്ക്കും F നും ഇടയിൽ)

Characteristics of the image:

• Inverted (തലകീഴായത്)
• Smaller than the object (ചെറുത്)
• Real (യഥാർത്ഥം)

• Object is to C:
Position of the image: At C (C-യിൽ)

Characteristics of the image:

• Inverted (തലകീഴായത്)
• Same size as the object (ഒരേ വലിപ്പം)
• Real (യഥാർത്ഥം)

• Object between C and F (C യ്ക്കും F നും ഇടയിൽ)

Position of the image: Beyond C (C-ക്ക് അപ്പുറം)

Characteristics of the image:

• Inverted (തലകീഴായത്)
• Larger than the object (വലുത്)

Real (യഥാർത്ഥം)

• Object at F (F – ൽ)

Position of the image: At infinity (അന ന്തതയിൽ)
Characteristics of the image:

• Inverted (തലകീഴായത്)
• Very large (വളരെ വലുത്)
• Real (യഥാർത്ഥം)

• Object between F and P (F-നും P-നും P-യ്ക്കും ഇടയിൽ)

Position of the image: Behind the mirror (ദർപ്പണത്തിന് പിന്നിൽ)
Characteristics of the image:

• Erect (നിവർന്നത്)
• Larger than the object (വലുത്)
• Virtual (മിഥൃ)

• Discuss the characteristics of real and virtual images and complete the table given below.

Answer:

Real Image	Virtual Image
Inverted	Erect
Can be caught on a screen	Cannot be caught on a screen
Formed in front of the mirror	Formed behind the mirror
Formed by the actual intersection of reflected rays	Formed where reflected rays appear to intersect

Class 8 Basic Science Chapter 12 Question Answer Extended Activities

Question 1.
Present a seminar on the uses of spherical mirrors in daily life and the devices that include spherical mirrors.
Answer:
Torches/Flashlights – Concentrates the light from a small bulb into a powerful, straight beam to illuminate distant objects.

Headlights of Cars Generates a strong, parallel beam to provide maximum visibility on the road.

Searchlights – Used in defense, rescue operations, and stage lighting to project a high-intensity beam over long distances.

Spherical Mirrors Class 8 Notes

Class 8 Basic Science Spherical Mirrors Notes Kerala Syllabus

Curved mirrors
A smooth curved surface can also form images like a plane surface. (നിരപ്പായ ദർപ്പണങ്ങൾ), which we use every day. However, images can also be formed by curved surfaces.

Spherical Mirrors (ഗോളീയ ദർപ്പണങ്ങൾ)
Mirrors whose reflecting surface forms a part of a sphere are called spherical mirrors.
ഒരു ഗോളത്തിന്റെ (sphere) ഭാഗമായ ദർപ്പണങ്ങ ളെയാണ് (mirrors) ഗോളീയ ദർപ്പണങ്ങൾ എന്ന് പറയുന്നത്. ഒരു സ്പൂണിന്റെ ഉൾഭാഗവും പുറംഭാ ഗവും ഗോളീയ ദർപ്പണങ്ങൾക്ക് ഉദാഹരണമാണ്.

Types of Spherical Mirrors
There are two main types of spherical mirrors:

Concave Mirror (കോൺകേവ് ദർപ്പണം)
Spherical mirrors with a reflecting surface curved inward are called concave mirrors.
Example: The inner side of a spoon (“cave” side) or the mirror in Fig. 12.9.
Property: A concave mirror generally converges (ഒരു ബിന്ദുവിലേക്ക് അടുപ്പിക്കുന്നു) light rays that fall on it.

Convex Mirror (കോൺവെക്സ്)
Spherical mirrors with a reflecting surface curved outward are called convex mirrors.
Example: The outer side of a spoon or the mirror in Fig. 12.10.
Property: A convex mirror generally diverg- es (വിവിധ ദിശകളിലേക്ക് അകറ്റുന്നു) light rays
that fall on it.

Important Terms for Spherical Mirrors

Centre of Curvature (C) (വക്രതാ കേന്ദ്രം):

• A spherical mirror is part of an imaginary sphere. The centre of this sphere is called the centre of curvature.
• It is represented by the letter C in diagrams.

Radius of Curvature (R) (വക്രതാ ആരം):

• The radius of the imaginary sphere of which the mirror is a part.
• In Fig. 12.9 & 12.10, the lines CP, CB, and CA all represent the radius of curvature.

Pole (P) (പോൾ):

• The midpoint of the reflecting surface of the spherical mirror.
• It is represented by the letter P in diagrams.

Aperture

• The diameter of the circular reflecting surface of a spherical mirror.
• In Fig. 12.9, the distance from A to B (along the curve) represents the reflecting surface, and its diameter is the aperture.

Principal Axis(മുഖ്യ അക്ഷം):

• The imaginary straight line connecting the centre of curvature (C) and the pole (P) of the mirror.
• C (വക്രതാ കേന്ദ്രം); ദർപ്പണം ഏത് ഗോളത്തി ന്റെ ഭാഗമാണോ, ആ ഗോളത്തിന്റെ കേന്ദ്രം.
• R (വകതാ ആരം): ആ ഗോളത്തിന്റെ ആരം (radius).
• P (പോൾ): ദർപ്പണത്തിന്റെ പ്രതിപതിക്കുന്ന പ തലത്തിന്റെ (reflecting surface)മധ്യബിന്ദു.
• (മുഖ്യ അക്ഷം). C-യെയും P-യെയും തമ്മിൽ ബന്ധിപ്പിക്കുന്ന നേർ രേഖ.

Reflection in Spherical Mirrors (ഗോ ളീയ ദർപ്പണങ്ങളിലെ പ്രതിപതനം)
The laws of reflection that apply to plane mirrors are also applicable to spherical mirrors.

• The Law of Reflection: For all mirrors, the angle of incidence (i) is equal to the angle of reflection (r).
• The activity in Fig. 12.11 confirms this. If you shine a ray at an angle of 30°, it will reflect at 30°.

ഒരു നിരപ്പായ കണ്ണാടി (plane mirror) പോലെ mom, conglo Borgen (spherical mirrors) പ്രകാശത്തിന്റെ പ്രതിപതന നിയമങ്ങൾ (laws of reflection) ബാധകമാണ്. അതായത്, പ തിക്കുന്ന കോണും (angle of incidence) പ്ര തിപതന കോണും (angle of reflection) എപ്പോ ഴും തുല്യമായിരിക്കും.

Principal Focus (F) and Focal Length (f)
This is a very important property that defines how a mirror bends light.

Concave Mirror (കോൺകേവ് ദർപ്പണം)

• In a concave mirror, light rays that fall parallel to the principal axis converge (ഒത്തുചേരുന്നു) to a single point on the principal axis after reflection. This point is called the principal focus (F).
• Real Focus: The focus of a concave mirror is Real ((യഥാർത്ഥം)). This is because the light rays actually meet at that point. You can prove this by holding a paper at F and seeing the light converge to a bright spot.

• Convex Mirror (കോൺവെക്സ് ദർപ്പണം)
  
• In a convex mirror, light rays that fall parallel to the principal axis appear to diverge (അകന്നുപോകുന്നു) from a particular point on the principal axis after reflection. This point is called the principal focus (F).
• Virtual Focus: The focus of a convex mirror is Virtual (മിഥു). This is because the rays do not actually meet; they only appear to be coming from a point behind the mirror.

Focal Length (f) (ഫോക്കസ് ദൂരം)
• The distance from the pole (P) of the mirror to the principal focus (F) is called the focal length (f).

Relationship between Focal Length (f) and Radius of Curvature (R)
For spherical mirrors, the focal length is exactly half of its radius of curvature.
Formula: f = R/2

Image Formation in Spherical Mirrors Using Ray Diagrams (ചിത്രങ്ങൾ ഉപയോഗിച്ച് പ്രതിബിംബ രൂപീകരണം)
To find the position and nature of an image, we can draw ray diagrams. These diagrams use a few simple rules for rays of light, all based on the law of reflection (∠i = ∠r).
Any line drawn from the Centre of Curvature (C) to the mirror is perpendicular (normal) to the mirror’s surface at that point.

The 4 Rules for Drawing Ray Diagrams:


Image Formation by a Concave Mirror
• Object is at infinity (വസ്തു അനന്തതയിൽ)

• Position of the image: At F (ഫോക്കസിൽ)
Characteristics of the image:

• Inverted (തലകീഴായത്)
• Smaller than the object (വളരെ ചെറുത്)
• Real (യഥാർത്ഥം)

• Object is Beyond C:

Position of the image: Between C and F (Cയ്ക്കും Fനും ഇടയിൽ)
Characteristics of the image:

• Inverted (തലകീഴായത്)
• Smaller than the object (ചെറുത്)
• Real (യഥാർത്ഥം)

• Object is at C:
Position of the image: At C (C-യിൽ)

Characteristics of the image:

• Inverted (തലകീഴായത്)
• Same size as the object (ഒരേ വലിപ്പം)
• Real (യഥാർത്ഥം)

• Object between C and F (C-യ്ക്കും Fനും ഇടയിൽ)

Position of the image: Beyond C (C-ക്ക് അപ്പുറം)
Characteristics of the image:

• Inverted (തലകീഴായത്)
• Larger than the object (വലുത്)
• Real (യഥാർത്ഥം)

• Object at F (F – ൽ)

Position of the image: At infinity (അനന്തതയിൽ)
Characteristics of the image:

• Inverted (തലകീഴായത്)
• Very large (വളരെ വലുത്)
• Real (യഥാർത്ഥം)

• Object between F and P (F-നും P-നും P-യ്ക്കും ഇടയിൽ)

Position of the image: Behind the mirror (ദർപ്പണത്തിന് പിന്നിൽ)
Characteristics of the image:

• Erect (നിവർന്നത്)
• Larger than the object (വലുത്)
• Virtual (മിഥു)

Position of the object	Position of the image	Size of the image	Nature of the image
At infinity	At the focus F	Highly diminished, point-sized	Real and inverted
Beyond C	Between F and C	Diminished	Real and inverted
AtC	AtC	Same size	Real and inverted
Between C and F	Beyond C	Enlarged	Real and inverted
At F	At infinity	Highly enlarged	Real and inverted
Between P and F	Behind the mirror	Enlarged	Virtual and erect

Image Formation by a Convex Mirror
Convex mirrors are simpler. No matter where the object is placed in front of it, the image is always the same type.

Characteristics of the image:

• Virtual
• Erect
• Smaller than the object

Real Images vs. Virtual Images (യഥാർത്ഥവും മിഥ്യയുമായ പ്രതിബിം)
Real Images: These are images that can be caught on a screen (e.g., the image of a candle formed on the white screen in Fig. 12.14). Real images are typically inverted (തലകീഴായവ).

Virtual Images: These are images that can- not be caught on a screen (e.g., the image you see of yourself in a plane mirror). Virtual images are typically erect (നിവർന്നവ).

Real Image	Virtual Image
Inverted	Erect
Can be caught on a screen	Cannot be caught on a screen
Formed in front of the mirror	Formed behind the mirror
Formed by the actual intersection of reflected rays	Formed where reflected rays appear to intersect

ഒരു സ്ക്രീനിൽ (Screen) പതിപ്പിക്കാൻ കഴിയുന്ന പ്രതിബിംബങ്ങളെ യഥാർത്ഥ പ്രതിബിംബം (Real Image) എന്ന് പറയുന്നു. സ്ക്രീനിൽ പതിപ്പിക്കാൻ കഴിയാത്തതും, ദർപ്പണത്തിനുള്ളിൽ കാണുന്നതു മായ പ്രതിബിംബങ്ങളെ മിഥ്യാ പ്രതിബിംബം (Virtual Image) എന്ന് പറയുന്നു.

Magnification (ആവർധനം)
The size of the image formed by a spherical mirror changes depending on the object’s position. Magnification is the measure of how large or small the image is compared to the object.
The ratio of the height of the image (h) to the height of the object (h) is called magnification (m).
Formula:
m = \(\frac{\text { Height of the image }}{\text { Height of the object }}\) = \(\frac{h_1}{h_0}\)

Sign Convention for Magnification:
To know if the image is erect (നിവർന്നത്) or inverted (തലകീഴായത്), we use a sign convention:

• Measurements above the principal axis (like an erect object or erect image) are considered positive (+).
• Measurements below the principal axis (like an inverted image) are considered. negative (-).

Interpreting the value of ‘m’:

• If m is negative (-): The image is invert- ed and real.
• If m is positive (+): The image is erect and virtual.
• If the value of m is greater than 1 (e.g., 2, -3): The image is larger (magnified). If the value of m is less than 1 (e.g., 0.5, -0.4): The image is smaller (diminished).

ആവർധനം (m) എന്നത് പ്രതിബിംബത്തിന് വസ് തുവിനേക്കാൾ എന്ത് വലിപ്പമുണ്ട് എന്ന് കാണിക്കു ന്ന ഒരു സംഖ്യയാണ്.
m ഒരു പോസിറ്റീവ് (+) സംഖ്യയാണെങ്കിൽ, പ്രതി ബിംബം നിവർന്നതും (erect) മിഥ്യയും (virtual) ആയിരിക്കും.
m ഒരു നെഗറ്റീവ് (-) സംഖ്യയാണെങ്കിൽ, പ്രതിബിം ബം തലകീഴായതും (inverted) യഥാർത്ഥവും (real) ആയിരിക്കും.

Uses of Spherical Mirrors in Daily Life (ഗോളീയ ദർപ്പണങ്ങളുടെ ഉപയോഗങ്ങൾ)
Spherical mirrors have many uses in our daily life.

Uses of Concave Mirrors (കോൺകേവ് ദർപ്പ ണത്തിന്റെ ഉപയോഗങ്ങൾ)
Concave mirrors are used when we need to converge light or get a magnified image.
• Shaving Mirror / Makeup Mirror / Dentist’s Mirror:
When an object (like a face or a tooth) is placed very close to the mirror (between the pole P and focus F), a concave mirror forms an enlarged, erect, and virtual image. This allows for a clear, magnified view.

• Flashlights and Vehicle Headlights:
Light rays that start from the principal focus (F) will, after reflection, travel parallel to the principal axis. The bulb is placed exactly at the focus (F) to produce a strong, parallel beam of light that can travel a long distance.

• Solar Thermal Power Plants Large concave mirrors (or reflectors) are used to collect sunlight. Rays of light from the sun (a distant object) come parallel to the principal axis and converge at the principal focus (F) after reflection. This concentrates a huge amount of solar energy at one point, generating intense heat to create steam.

Uses of Convex Mirrors (കോൺവെക്സ് ദർപ്പണത്തിന്റെ ഉപയോഗങ്ങൾ)
Convex mirrors are used when we need to diverge light or get a wider field of view.
• Rear-view/Side-view Mirrors in Vehicles:
Reason: A convex mirror always forms a small, erect, and virtual image. Because the image is small, it can cover a much wider field of view than a plane mirror, allowing the driver to see more of the road and traffic behind them.

Warning: “OBJECTS IN THE MIRROR ARE CLOSER THAN THEY APPEAR”. This warning is needed because the small, diminished image can make our brain think the car behind is farther away than it actually is.

• Road Safety Mirrors (on sharp turns):
Reason: Large convex mirrors are placed on blind corners and sharp turns so drivers can see oncoming traffic from beyond the curve, helping to reduce accidents.

• Reflectors in Street Lamps:
Reason: A convex mirror is placed above the bulb to diverge (spread) the light rays over a wider area of the street.

The comprehensive approach in SCERT Class 8 Basic Science Textbook Solutions Chapter 12 Spherical Mirrors Important Questions ensure conceptual clarity.

Spherical Mirrors Extra Questions and Answers Class 8 Basic Science Chapter 12 Kerala Syllabus

Spherical Mirrors Class 8 Important Questions

Question 1.
The midpoint of the reflecting surface of a spherical mirror is called the:
a) Centre of Curvature
b) Principal Focus
c) Pole
d) Aperture
Answer:
(c) Pole.

Question 2.
A spherical mirror with a reflecting surface curved inward is called:
a) Convex mirror
b) Concave mirror
c) Plane mirror
d) Aperture
Answer:
(b) Concave mirror.

Question 3.
For a spherical mirror with a small aperture, what is the relationship between focal length (f) and radius of curvature (R)?
a) f = R
b) f = 2R
c) f = \(\frac{R}{2}\)
d) f = R/4
Answer:
(c) f = \(\frac{R}{2}\)

Question 4.
Statement 1: In a concave mirror, light rays that fall parallel to the principal axis converge to a particular point on the principal axis after reflection.
Statement 2: In a convex mirror, light rays that fall parallel to the principal axis also converge to a particular point on the principal axis after reflection.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
b) Only Statement 1 is correct. (Statement 2 is incorrect; in a convex mirror, they appear to diverge from the focus).

Question 5.
Statement 1: Real images are those that can be caught on a screen.
Statement 2: Virtual images are also those that can be caught on a screen.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
b) Only Statement 1 is correct. (Statement 2 is incorrect; virtual images cannot be caught on a screen).

Question 6.
Complete the table comparing real and virtual images based on the text book.

Real Image	Virtual Image
Inverted	……….(a)……….
……….(b)……….	Cannot be caught on a screen
Formed in front of the mirror	……….(c)……….

Answer:

Real Image	Virtual Image
Inverted	(a) Erect
(b) Can be caught on a screen	Cannot be caught on a screen
Formed in front of the mirror	(c) Formed behind the mirror

Question 7.
Classify the following applications based on the type of spherical mirror used (Concave mirror / Convex mirror):
(Shaving mirror, Rear-view mirror in vehicles, Dentist’s mirror, Reflectors in street lamps)
Answer:
Concave mirror: Shaving mirror, Dentist’s mirror.
Convex mirror: Rear-view mirror in vehicles, Reflectors in street lamps.

Question 8.
Statement 1: A convex mirror always forms a small and erect image.
Statement 2: The image formed by a convex mirror is a real image.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
b) Only Statement 1 is correct. (Statement 2 is incorrect; the image is virtual).

Question 9.
Match the following image characteristics to the correct mirror type.
a) Virtual, smaller than the object
b) Virtual, larger than the object
c) Real, smaller than the object
Answer:
a) Convex Mirror
b) Concave Mirror
c) Concave Mirror

Question 10.
Find and correct the error in this statement:
“Magnification is the ratio of the height of the object (h_o) to the height of the image (h_i).”
Answer:
Error: The ratio is described incorrectly.
Correction: Magnification is the ratio of the height of the image (h_i) to the, height of the object (h_o).

Question 11.
Find and correct the error in this statement:
“In a flashlight, a convex mirror is used to create a parallel beam of light.”
Answer:
Error: Convex mirror.
Correction: In a flashlight, a concave mirror is used to create a parallel beam of light.

Question 12.
Find and correct the error in this statement:
“When calculating magnification, measurements below the principal axis should be considered positive.”
Answer:Error: Positive.
Correction: Measurements below the principal axis should be considered negative.

Question 13.
Why are convex mirrors used as rear-view mirrors in vehicles instead of plane mirrors?
Answer:
A convex mirror always forms an erect and small image. Because the image is smaller, it provides a much wider field of view than a plane mirror, allowing the driver to see more of the road and traffic behind them.

Question 14.
In a vehicle headlight, the bulb is placed at the principal focus of the concave mirror. Why?
Answer:
This is because light rays that start from the principal focus (F) of a concave mirror travel parallel to the principal axis after reflection. This property is used to send out a strong, parallel beam of light that can travel a long distance.

Question 15.
Why is the warning “OBJECTS IN THE MIRROR ARE CLOSER THAN THEY APPEAR” written on vehicle side mirrors?
Answer:
A convex mirror always forms a small image. This makes the driver feel that the vehicles coming from behind are at a great distance, even when they are not. The warning is there to prevent accidents caused by this misperception.

Question 16.
A concave mirror has a focal length of 15 cm. What is its radius of curvature?
Answer:
f = \(\frac{R}{2}\)
R = 2f
= 2 × 15 = 30 cm

Question 17.
A concave mirror produces an image that is the same size as the object. If the object is placed 40 cm from the mirror, what is the mirror’s focal length?
Answer:
An image of the same size is formed only when the object is placed at the Centre of Curvature (C).
This means the object distance is the Radius of Curvature. So, R = 40 cm Since f = R/2, the focal length f = 40 cm / 2 = 20 cm.

Question 18.
An object with a height of 10 cm is placed in front of a concave mirror. It produces an inverted image with a height of 5 cm. What is the magnification (m)?
Answer:
Height of object (h_o) = 10 cm. (This is measured above the axis, so it is positive).
Height of image (h_i) = 5 cm. (It is inverted, so it is measured below the axis, making it negative).
Answer:
m = h_i / h_o
m = -5 cm / 10 cm = -0.5.

Question 19.
Describe a simple procedure to find the approximate focal length of a concave mirror using a distant object (like the sun or a faraway building)
Answer:

• Hold the concave mirror and face it towards a distant object (like the sun).
• Hold a sheet of paper (to act as a screen) in front of the mirror.
• Light rays from a distant object travel parallel to the principal axis.
• Adjust the position of the paper until you get the smallest and sharpest image of the distant object (a bright point if using the sun).
• This image is formed at the principal focus (F).
• Measure the distance from the mirror’s surface (Pole, P) to the paper (F) using a scale. This distance is the focal length (f) of the mirror.

Question 20.
You are given a concave mirror and a convex mirror, but you don’t know which is which. Describe a simple test to identify them by looking at your own image.
Answer:

• Bring your face very close to the first mirror.
• Observe the image.
• If the image is large, erect, and virtual (magnified), it is the Concave Mirror.
• If the image is small, erect, and virtual, it is the Convex Mirror.
• (Alternative) Try to form an image of a distant window on a wall. The mirror that forms a real, inverted image on the wall is the Concave Mirror. The convex mirror cannot form a real image.

Question 21.
Describe the path of a light ray traveling parallel to the principal axis after it reflects from:
a) a concave mirror
b) a convex mirror
Answer:
a) In a concave mirror, a light ray that falls parallel to the principal axis will pass through the principal focus (F) after reflection.
b) In a convex mirror, a light ray that falls parallel to the principal axis will reflect as if it is diverging from the principal focus (F) located behind the mirror.

Question 22.
Complete the table

NO	Angle of incidence	Angle of reflection
1	30°	……….(a)……….
2	……….(b)……….	40°
3	50°	……….(c)……….
4	60°	……….(d)……….

Answer:
a. 30°
b. 40°
c. 50°
d. 60°

Question 23.
If the radius of curvature of a concave mirror is 24 cm what is its focal length?
Answer:
R = 24 cm
f = \(\frac{R}{2}\) = \(\frac{24}{2}\) = 12 cm

Question 24.
Find the radius of curvature of a convex mirror of focal length 0.6m
Answer:
f = \(\frac{R}{2}\)
0.6 = \(\frac{R}{2}\) = o.6 × 2 = 1.2 m

Question 25.
Write the characteristics of the image formed by an object placed at the centre of curvature of a concave mirror?
Answer:
Position: At the centre of curvature at the same side
Size: Same as the size of the object Nature: Real, Inverted

Question 26.
Complete the figure

Answer:

Question 27.
Complete the table

Path of incident Ray	Path of reflected ray
	Concave mirror	Convex mirror
Path of incident Ray	……. a ……..	……. b …….
Parallel to pricipal axis	…….. c …….	……. d …….
Through/to principal focus	…….. e …….	…….. f ……..
Through centre of curvature	…….. g …….	…….. h …….

Answer:
a. Passes through principal focus
b. Seem to come from the principal focus
c, d. Returns parallel to the principal axis
e, f. Returns through the same path
g, h. Reflects in the same angle of incident ray.

Question 28.
Write uses of concave mirrors
Answer:

1. As shaving mirror
2. As make up mirror
3. As head mirrors used by doctors
4. In film projectors

Question 29.
Examine the position of the object given in the figure and table the following peculiarities

a. position of the image
b. size of the image
c. nature of the image
Answer:
a. Behind the mirror.
b. Larger than the object.
c. Erect and virtual

Question 30.
Write the uses of convex mirror
Answer:

• As reflector in the street light
• As rear view mirror
• In search lights

Question 31.
Which type of spherical mirror is used as rear view mirror in vehicles?
(concave mirror, convex mirror, plane mirror)
Answer:
Convex

Question 32.
a. Complete the ray diagram of image formation of the object OB placed in front of the mirror.

b. Write two features of the image formed?
Answer:
a.
b. Virtual, erect and diminished.

Question 33.
Which mirror is called a converging mirror?
(a) Plane Mirror
(b) Concave Mirror
(c) Convex Mirror
(d) Spherical Mirror
Answer:
(b) Concave Mirror

Question 34.
The rear-view mirror in a car is a:
(a) Concave Mirror
(b) Plane Mirror
(c) Convex Mirror
(d) Cylindrical Mirror
Answer:
(c) Convex Mirror

Question 35.
The image formed by a convex mirror is always:
(a) Real and Inverted
(b) Virtual and Magnified
(c) Virtual and Diminished
(d) Real and Diminished
Answer:
(c) Virtual and Diminished

Question 36.
If the Radius of Curvature (R) of a spherical mirror is 50 cm, its focal length (f) is:
(a) 100 cm
(b) 50 cm
(c) 25 cm
(d) 12.5 cm
Answer:
(c) 25 cm (f = R/2 = 50/2)

Question 37.
A concave mirror can form a real, inverted, and same-size image when the object is placed at:
(a) Focus (F)
(b) Centre of Curvature (C)
(c) Pole (P)
(d) Infinity
Answer:
(b) Centre of Curvature (C)

Question 38.
Define the terms Pole (P) and Principal Focus ($F$) for a spherical mirror.
Answer:
Pole (P): The geometrical centre of the spherical mirror’s reflecting surface.
Principal Focus (F): The point on the principal axis where light rays parallel to the principal axis meet (concave) or appear to diverge from (convex) after reflection.

Question 39.
A dentist uses a specific type of spherical mirror.
(a) Name the mirror.
(b) Why is this mirror preferred by dentists?
Answer:
a) Concave Mirror.
b) It forms a magnified, erect, and virtual image of the tooth when held close, allowing the dentist to see details clearly.

Question 40.
Differentiate between a Real Image and a Virtual Image.
Answer:
Real Image: Formed when light rays actually meet after reflection. Can be obtained on a screen. Virtual Image:
Formed when light rays only appear to meet behind the mirror. Cannot be obtained on a screen.

Question 41.
State the two primary reasons why a convex mirror is used as a rear-view mirror in vehicles.
Answer:
A convex mirror is preferred because:

1. It always forms an erect (upright) image, which is easier for the driver to interpret.
2. It provides a much wider field of view because its reflective surface curves outward, allowing the driver to see more of the surrounding traffic.

Question 42.
A concave mirror is used in a solar furnace. Explain the principle behind this use.
Where must the solar heater coil be placed to get maximum heat?
Answer:
Principle: Concave mirrors are converging mirrors. They take the nearly parallel rays of light coming from the sun (a distant source) and reflect them to converge at a single point.

Placement: The solar heater coil must be placed at the Principal Focus (F) of the concave mirror. This ensures ail the reflected solar energy is concentrated into the smallest possible area, producing maximum heat.

Question 43.
Complete the following table for a Concave Mirror:

Position of the Object	Position of the image	Characteristics of the Image
At Infinity	At F	Highly Diminished, Real, inverted
Between C and F	?	?
Between F and P	?	Magnified, Erect, Virtual

Answer:

Position of the Object	Position of the image	Characteristics of the Image
At Infinity	At F	Highly Diminished, Real, inverted
Between C and F	Beyond C	Magnified, Real, Inverted
Between F and P	Behind the Mirror	Magnified, Erect, Virtual

Reviewing SCERT Class 8 Basic Science Solutions and Kerala Syllabus Class 8 Basic Science Chapter 11 Magnetism and Electricity Question Answer Notes Pdf can uncover gaps in understanding.

Class 8 Basic Science Chapter 11 Magnetism and Electricity Question Answer Notes

Class 8 Basic Science Chapter 11 Notes Kerala Syllabus Magnetism and Electricity Question Answer

Magnetism and Electricity Class 8 Questions and Answers Notes

Let’s Assess

Question 1.
A student is trying to make a device to find direction using a magnetic needle. For this, he places the magnetic needle inside a box made of iron.
a) Will this device work properly?
b) Explain your answer.
c) What changes should be made to make this device work properly?
Answer:
a) No, the device will not work properly.

b) Iron is a magnetic material with high permeability. This means it allows the Earth’s magnetic field lines to pass through it very easily. The iron box will attract all the magnetic field lines, causing them to pass through the walls of the box instead of passing through the inside. The compass needle inside will be shielded from the Earth’s magnetic field and will not align to the North-South direction. This is called magnetic shielding.

c) The box should be made of a non-magnetic material (an insulator) that does not interfere with magnetic field lines. Examples: A box made of plastic, cardboard, wood, or aluminum.

Question 2.
AB is a bar magnet shown in the figure below. An iron rod CD is placed near its B pole.
• Which magnetic poles will be formed at the ends C and D?
• Which property of magnets does this phenomenon demonstrate?

Answer:
This is an example of Magnetic induction.

• The pole nearer to the magnet gets the opposite polarity.
• The pole farther from the magnet gets the same polarity.

Therefore:

• End C (nearer to B’s South pole) will become a North pole (N).
• End D (farther from B’s South pole) will become a South pole (S).

This phenomenon demonstrates Magnetic Induction. Magnetic Induction is the phenomenon where a magnetic substance acquires magnetism (Induced Magnetism) due to the presence of a magnet.

Question 3.
A bar magnet and a U magnet are shown in figures (a, b) each having two iron nails hanging from them.
a. Which is the correct figure in each case?
b. Explain the reason clearly.

Answer:
a.

• For the bar magnet: Figure A is correct.
• For the U-magnet: Figure B is correct.

b. Reason: The nails are magnetized by magnetic induction. When induced, the like poles (which form at the free ends of the nails) will repel each other.

In Figure A (Bar magnet): The magnet’s pole (e.g., North) induces an opposite pole (South) at the head of both nails and a like pole (North) at the tips. Since both tips are North poles, they repel each other and move apart.

In Figure B (U-magnet): The two poles of the U-magnet (N and S) are used. The nail on the N pole gets an S pole at its head and an N pole at its tip. The nail on the S pole gets an N pole at its head and an S pole at its tip. Since the free tips of the nails are now unlike poles (N and S), they will attract each other and move closer.

Question 4.
You are given a soft iron piece, a steel piece of the same size, insulated copper wire and a battery:
a. Suggest a method to make a powerful permanent magnet.
b. Suggest a method to make a temporary magnet.
Answer:
a. To make a permanent magnet, you must use the steel piece, which has high retentivity (the ability to retain magnetism).

• Method: Wrap the insulated copper wire around the steel piece many times to create a coil.
• Connect the ends of the wire to the battery and pass a strong electric current through it for some time.
• Even after the battery is disconnected, the steel will retain its magnetism.

b. To make a temporary magnet (an electromagnet), you must use the soft iron piece, which has high susceptibility (gets magnetized easily) but low retentivity (loses magnetism quickly).

• Method: Wrap the insulated copper wire around the soft iron piece.
• Connect the ends of the wire to the battery.
• The soft iron will become a strong magnet only as long as the electricity is flowing. It will lose its magnetism when the battery is disconnected.

Question 5.
In an experiment, a plastic car with an iron piece inside it, is made to run on a wooden table by sliding a strong magnet below it.
a) The experiment failed when a steel table was used. What is the reason for this?
b) If an aluminium table is used instead of steel, what will happen? Why?
Answer:
a) Reason: Magnetic Shielding.
Steel is a magnetic material (like iron). When the magnet is moved under the steel table, the steel table’s high permeability causes the magnetic field lines to pass through the table itself rather than passing above the table to reach the car. The steel table effectively shields the iron piece in the car from the magnet’s force, so the car does not move.

b) What will happen: The experiment will work.
Why: Aluminium is a non-magnetic material (like plastic or wood). It does not block or interfere with magnetic field lines. The magnetic field from the magnet will pass through the aluminium table easily and attract the iron piece in the car, making it move.

Basic Science Class 8 Chapter 11 Question Answer Kerala Syllabus

Textbook Page No : 186 & 187

Question 1.
Some situations in which magnets are used are given below. Add more situations.
Answer:

• MRI scanning machines
• Headphones and speakers
• Magnetic compass
• Electric motors
• Digital Compasses
• Electromagnets
• Maglev trains (Magnetic Levitation)

Question 2.
Some familiar magnets are given below. Complete the table.

Answer:

Textbook Page No : 188 & 189

Question 3.
What happens when the north pole of a magnet is brought near to the north Dole of another maanet?

observe the changes and complete the table.
Answer:

Activity	Observation
When the north poles are brought close to each other	Repels
When the north pole and the south pole are brought close to each other	Attracts
When the south poles are brought close to each other	Repels

Question 4.
Why is the pencil not falling down and floating in the air like this?
Answer:
The pencil is floating because of magnetic levitation. The magnetic force of repulsion between the magnets on the pencil and the magnets on the cardboard is strong enough to balance the force of gravity, causing the pencil to float in the air.

Question 5.
Can you move the pencil backward without touching it? How can it be possible?
Answer:
Yes, it’s possible. You can move the pencil by bringing another magnet near one of the floating magnets. If you bring a like pole (e.g., North pole to North pole), the repulsion will push the floating magnet and the pencil away.

Question 6.
What will happen if you bring another magnet near one side of the top magnet?
Answer:
It depends on which pole you bring close. If you bring a like pole near the top magnet, it will repel and move away. If you bring an unlike pole near it, it will attract and move towards the magnet you are holding.

Question 7.
Do you know if this special property of magnet is used in any technology?
Answer:
Maglev (Magnetic Levitation) Trains

Question 8.
What are Maglev trains?
Answer:
This is a major technology that uses magnetic levitation.

• Maglev trains are trains that run with out wheels.
• They use powerful electromagnets on the train and the track to repel each other.
• This levitates (suspends) the train above the track.
• Advantage: The absence of physical contact eliminates friction. This allows Maglev trains to reach extremely high speeds with minimal energy loss, and provides a quieter, smoother ride.

Textbook Page No : 190 & 191

Question 9.
When a bar magnet is suspended freely, in / which direction does it align?

Answer:
If a magnet can move freely, it always aligns in the north-south direction of the Earth.

Question 10.
Why does a magnetic compass always show the north-south direction?
Answer:
It is because of the influence of the Earth’s magnetic field. The Earth acts like a giant magnet with its own magnetic poles. The magnetic north pole of the Earth is near the geographic south pole, and the Earth’s magnetic south pole is near the geographic north pole.

Question 11.
How can we make an artificial magnet?
Answer:
You can make one by taking a magnetic material (like a hacksaw blade) and rubbing it with one pole of a strong magnet. You must rub it repeatedly in the same direction from one end to the other.

Textbook Page No : 192 & 193

Question 12.
How can you identify the poles of a ring magnet or a U-shaped magnet?
Answer:
You can use a magnetic compass (magnetic needle). If the north pole of the compass needle (often the red end) is repelled, that part of the magnet is a North pole. If the north pole of the compass is attracted, that part of the magnet is a South pole.

Question 13.
What is your conclusion after breaking a magnet into smaller pieces?
Answer:
No matter how small a magnet is, it will always have two poles (a north and a south pole). A magnet with only one pole (a monopole) does not exist.

Textbook Page No : 195 & 196

Question 14.
Is the distribution of magnetic field lines the same everywhere?
Answer:
No, the distribution of magnetic field lines is not the same everywhere around a magnet. The spacing of the lines indicates the strength of the magnetic field.

Question 15.
How is magnetic field strength related to magnetic field lines?
Answer:
The magnetic field is strongest where the magnetic field lines are closest together. These areas have a higher magnetic flux density.

Question 16.
What will happen to the magnetic flux if the size of the surface it passes through increases?
(Increase/ decrease)
Answer:
The magnetic flux will increase. Since magnetic flux is the total number of field lines passing perpendicular / normally through a surface, a larger surface will catch more lines.

Question 17.
Is the magnetic flux density higher at the poles of a magnet or at other places?
Answer:
The flux density is higher at the poles. The text states, “The poles of a magnet have the highest magnetic flux density.”

Question 18.
In the experiment with iron filings in a bottle (Fig 11.19), where do the filings stick the mo¬st and where do they stick the least?

Answer:
Most: The iron filings stick the most at the poles of the magnet.

Least: The filings are seen the least in the middle of the magnet, away from the poles. This happens because the magnetic field strength is greatest at the poles and gets weaker as you move away from them.

Textbook Page No : 197 & 198

Experiment (Fig. 11.20 & 11.21)

Question 19.
“Bring another pin near the free end of the first pin. Isn’t the second needle getting attracted?”
Answer:
Yes, the second pin gets attracted. This is because the first pin has become an induced magnet and can now attract other magnetic substances.

Question 20.
“Now, bring a magnetic compass near the free end of the needle. Isn’t the direction of the compass needle changing?”
Answer:
Yes, the direction of the compass needle changes. This confirms that the first pin has acquired Induced Magnetism and is acting as a magnet with defined poles.

Question 21.
“Then, carefully remove the first needle from the magnet. Does it still show magnetic properties? Write your observations in the science diary.”
Answer:
Observation: The first pin will still show some magnetic properties (attract paper clips or other pins) immediately after being removed, but this induced magnetism will be temporary and quickly weaken, depending on the material the pin is made of (e.g., iron or steel).

Question 22.
“What are the uses of magnetic induction? Discuss.”
Answer:

• Used in making electromagnets, where soft iron cores are induced to become temporary magnets.
• It is the principle by which a permanent magnet can attract non-magnetized magnetic objects (like iron nails).
• Used in magnetic separation techniques and the operation of certain electrical devices.

Question 23.
Which of these has greater susceptibility? (Soft iron/Steel)
Answer:
Soft iron.

Question 24.
Which of these has greater retentivity? (Soft iron/Steel)
Answer:
Steel

Textbook Page No : 199 & 200

Question 25.
Based on the characteristics you observed, which is more suitable for making strong temporary magnets, soft iron or steel?
Answer:
Soft iron is more suitable. Temporary magnets (electromagnets) need to acquire magnetism easily (high susceptibility) and lose it quickly (low retentivity) when the current or external field is removed.

Question 26.
When making permanent magnets, which magnetic property of steel should be utilised?
Answer:
The property of high retentivity should be utilised. Permanent magnets need to retain their magnetism for a long time.

Permeability and Experiment

Question 27.
What do you observe?
Answer:
Observation: When the iron filings are sprinkled and the plate is tapped, the filings will cluster around the magnets but will not stick to the area over the gap (the hole) in the large iron nut. The magnetic field lines are concentrated through the iron nut, bypassing the area where the air gap is.

Question 28.
Are the iron filings sticking to the area where the gap in the iron nut is present?
Answer:
No, the iron filings are not sticking to the area where the gap in the iron nut is present.

Question 29.
What conclusion do you reach?
Answer:
Conclusion: Soft iron (like the iron nut) has a higher ability than air to allow magnetic field lines to pass through it. The magnetic field lines prefer to travel through the path of least resistance, which is the soft iron, rather than the air gap.

Question 30.
Why do compass needles not show direction when placed inside a box made of soft iron?
Answer:
Explanation: Soft iron has very high permeability. When a compass is placed inside a soft iron box, the soft iron effectively diverts the Earth’s external magnetic field lines, causing them to pass through the box material instead of the air inside it. This magnetic shielding effect prevents the magnetic field from reaching the compass needle, so the needle cannot align itself with the Earth’s field and show direction.

Question 31.
Electromagnet Experiment; complete the table

Answer:

Experiment	Observation
When electricity flows, the soft iron piece and the paper clips	attracts
After removing the cell, the soft iron piece and the paper clips	does not attract

Question 32.
Based on this experiment, can you write down the different ways to increase the strength of an electromagnet?
Answer:

• Increasing the number of turns of the coil around the soft iron core.
• Increasing the current flowing through the coil (by increasing the number of cells/battery voltage).
• Increasing the cross-sectional area of the soft iron inside the coil.
• Using a core material with higher permeability (like soft iron).

Question 33.
Let’s write examples of devices that use electromagnets

Answer:

• Electric bells
• Loudspeakers
• Cranes (used to lift heavy iron objects)

Question 34.
What is the charge of the paint droplets?
Answer:

Electromagnets	Permanent Magnets
Poles can be changed	The gained magnetism can be retained for a long time
Magnetic strength can be changed/ varied (by changing the current or number of turns)	Magnetic strength cannot be increased

Class 8 Basic Science Chapter 11 Question Answer Extended Activities

Question 1.
What is the important role of neodymium magnets in electric vehicles (EVs)? How does the use of these magnets affect the vehicle’s efficiency, speed, and driving range? Collect information about this and prepare a report.
Answer:
Neodymium magnets are used to create permanent magnet synchronous motors (PMSM), which are highly efficient and powerful.

Efficiency: PMSMs with neodymium magnets are very efficient, converting a large percentage of electrical energy into mechanical energy.

Speed/Power: They allow for high power density, enabling faster acceleration and higher top speeds.

Driving Range: The high efficiency reduces energy consumption, leading to an extended driving range for the EV on a single charge.

Question 2.
Build a model of a vehicle that operates using magnetic levitation. Prepare a slide/chart explaining its working principle.
Answer:
This is a project-based activity involving building a model (e.g., a simple Maglev train model).

Working Principle (for the slide/chart): Magnetic levitation works using repulsive forces between magnets (either permanent magnets or electromagnets) to lift the vehicle above the track, eliminating friction. An electromotive force is then used to propel the vehicle forward.

Magnetism and Electricity Class 8 Notes

Class 8 Basic Science Magnetism and Electricity Notes Kerala Syllabus

Magnets are objects that can attract (ആകർഷിക്കുക) and repel (വികർഷിക്കുക) other objects. This property is called magnetism. Magnets are used in many devices.

Examples of Magnet Uses

• MRI scanning machines
• Headphones and speakers
• Magnetic compass
• Electric motors
• Maglev trains (Magnetic Levitation)

ആകർഷിക്കാനും വികർഷിക്കാനും കഴിവുള്ള വസ് തുക്കളാണ്. കാന്തങ്ങൾ. കാന്തിക ബലം ഉപയോഗി ച്ച് വസ്തുക്കളെ വായുവിൽ ഉയർത്തി നിർത്താൻ സാധിക്കും (Magnetic levitation).

Natural Magnets & Artificial Magnets

Natural Magnets (പ്രകൃതിദത്ത കാന്തങ്ങൾ)

• These are magnets that are obtained directly from nature.
• Example: Lodestone, Magnetite

Artificial Magnets (കൃത്രിമ കാന്തങ്ങൾ)

• These are magnets made by people in specific shapes, sizes, and strengths.
• They are typically made using metal alloys (ലോഹസങ്കരങ്ങൾ).

Types of Artificial Magnets
Artificial magnets are made from d materials.

• Alnico Magnets:
  These are alloys made from aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe).
• Ceramic/Ferrite Magnets
  These are made by mixing iron oxide with carbonates of elements like barium or strontium.
• Electromagnet
  This is a temporary magnet made by passing electricity through a wire coiled around a soft iron core.

General Properties of Magnets (കാന്തത്തിന്റെ പൊതുവായ സവിശേഷതകൾ)
1. Poles Exist in Pairs: Every magnet has two poles, a North pole (N) and a South pole (S). A magnet with only one pole (monopole) does not exist. If you break a magnet, each piece becomes a new, complete magnet (Each has two poles)
‘ഒരു കാന്തത്തെ എത്ര ചെറുതാക്കിയാലും, അതിന് എപ്പോഴും ഒരു ഉത്തരധ്രുവവും ദക്ഷിണധ്രുവവും ഉണ്ടായിരിക്കും. ഒരൊറ്റ ധ്രുവം (N or S) മാത്രമായി ഒരു കാന്തത്തിന് നിലനിൽക്കാൻ കഴിയില്ല.

2. Attraction & Repulsion: The fundamental law of magnetism is:

• Like poles repel ((സജാതീയ ധ്രുവങ്ങൾ വികർഷിക്കുന്നു.) (e.g., N-N or S-S).
• Unlike poles attract (വിജാതീയ ധ്രുവ ങ്ങൾ ആകർഷിക്കുന്നു) (e.g., N-S).

3. Directional Property: If a magnet is suspended freely (like being suspended by a string), it will always align itself with the Earth’s North-South direction.
ഒരു കാന്തത്തെ സ്വതന്ത്രമായി തൂക്കിയിട്ടാൽ, അത് എപ്പോഴും ഭൂമിയുടെ വടക്ക് തെക്ക് ദിശയിൽ വന്ന് നിൽക്കും. ഇതാണ് കാന്തത്തിന്റെ ദിശാസൂചക സ്വഭാവം.

Application: This is the working principle of a Magnetic Compass (വട ക്കുനോക്കിയന്ത്രം).).

• A compass is a device that uses this property.
• It contains a small magnetic needle that can rotate freely.
• This needle always points to the Earth’s North-South direction, allowing us to easily determine all other directions (East, West).

4. Magnetic Levitation: The repulsion of like poles can be used to make an object float, balancing the force of gravity (e.g., Maglev trains).

Maglev Trains

• This is a major technology that uses magnetic levitation.
• Maglev trains are trains that run without wheels.
• They use powerful electromagnets on the train and the track to repel each other.
• This levitates (suspends) the train above the track.
• Advantage: The absence of physical contact eliminates friction. This allows Maglev trains to reach extremely high speeds with minimal energy loss, and provides a quieter, smoother ride.

The Earth as a Giant Magnet (ഭൂമി ഒരു വൻകാന്തം)
The directional property of a compass works because the Earth itself acts like a big magnet, with its own magnetic field and poles.

• Cause of Earth’s Magnetism: This magnetic nature is believed to be caused by the movement of large amounts of molten iron and nickel in the Earth’s inner core.
• The “Pole-Swap”: The Earth’s magnetic poles are inverted compared to its geographic poles.
  1. The Earth’s Magnetic South Pole is located near the Geographic North Pole (the “top” of the world).
  2. The Earth’s Magnetic North Pole is located near the Geographic South Pole (the “bottom” of the world).
• How a Compass Works: A compass needle’s North pole is attracted to the Earth’s Magnetic South Pole (which is at our Geographic North). This is why a compass needle always points north!

ഭൂമി ഒരു വലിയ കാന്തമായി പ്രവർത്തിക്കുന്നു. ഭൂമിയുടെ കാന്തിക ദക്ഷിണ ധ്രുവം (Magnetic South Pole) അതിന്റെ ഭൂമിശാസ്ത്രപരമായ ഉത്ത ര ധ്രുവത്തിന് (Geographic North Pole) അടു ത്താണ്. ഒരു വടക്കുനോക്കിയന്ത്രത്തിലെ കാന്ത സൂചിയുടെ ഉത്തരധ്രുവം (N pole), ഭൂമിയുടെ ഈ കാന്തിക ദക്ഷിണ ധ്രുവത്താൽ ആകർഷിക്ക പ്പെടുന്നു. ഇതുകൊണ്ടാണ് കാന്തസൂചി എപ്പോഴും വടക്ക് ദിശയിലേക്ക് തിരിഞ്ഞുനിൽക്കുന്നത്.

Magnetisation (കാന്തവൽക്കരണം)
We can create artificial magnets using a process called magnetisation. One common way is the “single-touch” method.

Procedure (Fig. 11.12):

1. Place a hacksaw blade on a table.
2. Take a strong bar magnet. Using one pole (e.g., the North pole), rub the blade starting from one end (A) to the other end (B).
3. Lift the magnet and bring it back to end A.
4. Repeat this process several times, always rubbing in the same direction (A to B).

• Result: The hacksaw blade will become a magnet. The end where the rubbing starts (A) will become the North pole, and the end where the rubbing ends (B) will become the South pole.

• Observation (Fig. 11.13): When a magnet is broken into smaller pieces, each piece instantly becomes a new, complete magnet with its own North pole and South pole.
• Conclusion: “No matter how small a magnet is, it will always have two poles. A magnet with only one pole does not exist.” (These single poles are called ‘monopoles’).

ഒരു കാന്തത്തെ ഏത് ചെറിയ കഷണങ്ങളായി മുറിച്ചാലും, ആ ഓരോ കഷണവും ഒരു പൂർണ്ണ കാന്തമായിരിക്കും (അതിന് സ്വന്തമായി ഒരു നോ ർത്ത് പോളും സൗത്ത് പോളും ഉണ്ടാകും). ഒരു ധ്രുവം (Nor S) മാത്രമുള്ള ഒരു കാന്തത്തെ (magnetic monopole) നിർമ്മിക്കാൻ സാധ്യമല്ല.

Magnetic Field and Field Lines (കാന്തിക മണ്ഡലവും മണ്ഡലരേഖകളും)
Magnetic Field
The region around a magnet where its force can be felt is called the magnetic field.

Magnetic Field Lines (Fig. 11.16):

• Definition: These are imaginary lines used to represent the direction and strength of a magnetic field.
• Properties:
  1. They are closed loops.
  2. Outside the magnet, their direction is always from the North pole to the South pole.
  3. Where the lines are closer together (at the poles), the magnetic field is stronger.
• How to Draw Field Lines (Experiment):
  1. Place a bar magnet on a piece of paper.
  2. Place a magnetic compass near the North pole.
  3. Put a dot on the. paper where the north tip of the compass needle points.
  4. Move the compass so its south tip is at the dot you just made.
  5. Repeat this process, making new dots, until you reach the South pole.
  6. Connect the dots to draw a single magnetic field line.

ഒരു കാന്തത്തിന് ചുറ്റും അതിന്റെ ശക്തി (ആകർ ഷണ/വികർഷണ ബലം അനുഭവപ്പെടുന്ന മേഖല യാണ് കാന്തിക മണ്ഡലം (Magnetic Field), ഈ കാന്തിക മണ്ഡലത്തെ ചിത്രീകരിക്കാൻ ഉപയോഗി ക്കുന്ന സാങ്കൽപ്പിക രേഖകളാണ് കാന്തിക മണ്ഡല രേഖകൾ (Magnetic Field Lines). ഈ രേഖകൾ കാന്തത്തിന് പുറത്ത് എപ്പോഴും നോർത്ത് പോളിൽ നിന്ന് ആരംഭിച്ച് സൗത്ത് പോളിൽ അവസാനിക്കുന്നു.

Magnetic Field Strength and Magnetic Flux Density
These terms describe how strong a magnetic field is.

Magnetic Field Strenth

This is how strong the magnet’s influence is. The iron filing experiment (Fig. 11.19) shows that the magnetic field strength is greatest at the poles and gets weaker as you move away.

Magnetic Flux ((കാന്തിക ഫ്ളക്സ്))

• Definition: “The total number of magnetic field lines passing normally (perpendicularly) through a given surface”.

• If the size of the flat surface in Fig 11.18 increases, the magnetic flux passing through it will also increase.

Magnetic Flux Density (കാന്തിക ഫ്ളക്സ് ഡെൻസിറ്റി)

• Definition: “The number of magnetic field lines passing normal through a unit area…”.
• This is a measure of how concentrated or dense the field lines are.
• Key Relationship: Magnetic flux density is higher where the magnetic field strength is more. Since the field strength is greatest at the poles (where iron filings stick the most), the poles of a magnet have the highest magnetic flux density.
• മാഗ്നറ്റിക് ഫ്ളക്സ് ഒരു പ്രതലത്തിലൂടെ ലംബ മായി കടന്നുപോകുന്ന കാന്തിക മണ്ഡല രേഖക ളുടെ ആകെ എണ്ണമാണ് (Total number) ഫ്ളക്സ്.
• മാഗ്നറ്റിക് ഫ്ളക്സ് ഡെൻസിറ്റി: ഒരു നിശ്ചിത വിസ്തീർണ്ണത്തിൽ (Unit Area) എത്രമാത്രം മണ്ഡലരേഖകൾ ഉണ്ട് (അവയുടെ ‘തിക്ക്’. ‘അ ടുപ്പം’) എന്നതാണ് ഫ്ളക്സ് ഡെൻസിറ്റി.
• കാന്തത്തിന്റെ ശക്തി (Strength) ഏറ്റവും കൂടു തലുള്ളത് ധ്രുവങ്ങളിൽ (poles) ആണ്. ഇവിടെ കാന്തിക മണ്ഡലരേഖകൾ വളരെ അടുത്തടുത്താ ണ് സ്ഥിതിചെയ്യുന്നത്. അതിനാൽ, കാന്തിക ശ ക്തി എവിടെയാണോ കൂടുതൽ, അവിടെ ഫ്ളക് സ് ഡെൻസിറ്റിയും കൂടുതലായിരിക്കും.

Magnetic Induction (കാന്തിക പ്രവേശനം)

This is the phenomenon of making a temporary magnet without touching it.

• Definition: “The phenomenon of a magnetic substance (like an iron pin) acquiring magnetism due to the presence of a magnet is known as Magnetic Induction”.
• The magnetism the substance (pin) gets is called Induced Magnetism.

Polarity of Induced Magnetism:

• The polarity of the induced magnet is fixed:
  • Unlike polarity develops at the nearer end.
  • Like polarity develops at the farther end.
• Example (Fig 11.21): The permanent magnet’s North pole (N) is near the pin.

• • The head of the pin (nearer end) gets the unlike pole: South pole (S).
  • The tip of the pin (farther end) gets the like pole: North pole (N).

ഒരു കാന്തത്തിന്റെ സാന്നിധ്യം (presence) മൂലം മറ്റൊരു കാന്തിക വസ്തുവിന് (magnetic substance, e.g., ആണ്) താൽക്കാലികമായി കാന്തശ ക്തി ലഭിക്കുന്ന പ്രതിഭാസമാണ് മാഗ്നറ്റിക് ഇൻഡക്ഷൻ.

പ്രത്യേകത: കാന്തത്തിന്റെ ഏത് ധ്രുവമാണോ അടു ത്തു കൊണ്ടുവരുന്നത്, അതിന് വിപരീത ധ്രുവം (unlike pole) ആയിരിക്കും ആണിക്ക് അറ്റത്ത് ലഭി ക്കുക. ആണിക്ക് മറ്റേ അറ്റത്ത് കാന്തത്തിന്റെ അതേ ധ്രുവം (like pole) ആയിരിക്കും ലഭിക്കുക.

Properties of Magnetic Materials (Soft Iron & Steel)
Different materials react to magnetic fields differently.

• Experiment (Fig 11.22 & 11.23):

• Soft Iron (പച്ചിരുമ്പ്): Gets magnetized easily when placed near a magnet. But when the magnet is removed, it quickly loses its magnetism.
• Steel (ഉരുക്ക്): Takes more time to get magnetised. However, even after the magnet is removed, it does not lose its magnetism quickly.
  This leads to four important properties:

Susceptibility

• Definition: The ability of magnetic materials to get magnetised due to the influence of an external magnetic field.
• Soft Iron has greater susceptibility.

Retentivity

• Definition: The ability to retain the magnetism.
• Steel has greater retentivity.

Permeability

• Definition: The ability of a substance to pass magnetic field lines through it.
• Soft Iron has a high permeability.

Soft Iron VS Steel (പച്ചിരുമ്പും ഉരുക്കും)

Material	Susceptibility (പെട്ടെന്ന് കാന്തമാകും)	Retentivity (കാന്ത ശക്തി നിലനിർത്തും)	Use (ഉപയോഗം)
Soft Iron	High	Low	Temporary magnets (e.g., Electromagnets)
Steel	Low	High	Permanent magnets

Applications:

• Soft Iron is suitable for making temporary magnets (like electromagnets) because of its high susceptibility and low retentivity.
• Steel is suitable for making permanent magnets because of its high retentivity.
• Magnetic Shielding: A compass placed inside a soft iron box will not show direction because soft iron’s high permeability forces the Earth’s magnetic field lines to pass through the box rather than the in-side, shielding the compass.

Electromagnets വൈദ്യുതകാന്തങ്ങൾ

• Definition: A temporary magnet made by passing electricity through an insulated wire coiled around a soft iron core.
• Property: Only magnetic when the cur¬rent is on.
• Uses: Electric bells, loudspeakers, MRI machines.
• Increasing Strength: You can make an electromagnet stronger by:
  1. Increasing the number of turns in the coil (ചുറ്റുകളുടെ എണ്ണം കൂട്ടുക).
  2. Increasing the strength of the current (വൈദ്യുതിയുടെ ശക്തി കൂട്ടുക).
  3. Increasing the cross-sectional area of the soft iron core (പച്ചിരുമ്പിന്റെ കനം കൂട്ടുക).

ഒരു പച്ചിരുമ്പ് കോറിന് (soft iron core) ചുറ്റും കവചിത ചാലകം (insulated wire) ഉപയോഗിച്ച് വൈദ്യുതി കടത്തിവിടുമ്പോൾ നിർമ്മിക്കപ്പെടുന്ന താൽക്കാലിക കാന്തങ്ങളാണ് വൈദ്യുതകാന്തങ്ങൾ. വൈദ്യുതി നിലയ്ക്കുമ്പോൾ ഇവയുടെ കാന്തശ ക്തി നഷ്ടപ്പെടുന്നു.

The comprehensive approach in SCERT Class 8 Basic Science Textbook Solutions Chapter 11 Magnetism and Electricity Important Questions ensure conceptual clarity.

Magnetism and Electricity Extra Questions and Answers Class 8 Basic Science Chapter 11 Kerala Syllabus

Magnetism and Electricity Class 8 Important Questions

Question 1.
Which material is most suitable for making a permanent magnet?
a) Soft Iron
b) Steel
c) Copper
d) Lodestone
Answer:
b) Steel. (It is used for permanent magnets due to its high retentivity).

Question 2.
The phenomenon of an object floating in the air using magnetic force to balance gravity is called:
a) Magnetic Induction
b) Magnetic Levitation
c) Magnetisation
d) Magnetic Permeability
Answer:
(b) Magnetic Levitation.

Question 3.
The ability of a magnetic material to get magnetized due to an external magnetic field is called:
a) Susceptibility
b) Permeability
c) Retentivity
d) Induction
Answer:
a) Susceptibility.

Question 4.
Statement 1: When a magnet is broken into two pieces, one piece will be a North pole and the other will be a South pole.
Statement 2: A freely suspended magnet aligns in the North-South direction because the Earth itself acts like a giant magnet.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
c) Only Statement 2 is correct. (Statement 1 is incorrect; each piece will be a new, complete magnet with both a North and South pole).

Question 5.
Statement 1: Magnetic field lines outside a magnet are directed from the South pole to the North pole. Statement 2: The magnetic field strength is greatest at the poles of a magnet.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
c) Only Statement 2 is correct. (Statement 1 is incorrect; they are directed from the North pole to the South pole).

Question 6.
Statement 1: Soft iron is used to make the core of an electromagnet because it has low retentivity and high susceptibility.
Statement 2: Steel is used to make permanent magnets because it has high retentivity.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
a) Both statements are correct.

Question 7.
Classify the following materials based on their primary use in magnetism (Permanent Magnet / Temporary Magnet):
(Soft Iron, Alnico, Steel, The core of an electric bell)
Answer:
Permanent Magnet: Alnico, Steel
Temporary Magnet: Soft Iron, The core of an electric bell (which is an electromagnet)

Question 8.
Categorize the following as Natural Magnets or Artificial Magnets: (Lodestone, Bar magnet, Electromagnet, Horseshoe magnet. Ceramic magnet)
Answer:
Natural Magnets: Lodestone
Artificial Magnets: Bar magnet, Electromagnet, Horseshoe magnet, Ceramic magnet

Question 9.
Find and correct the error in this statement:
“A magnetic compass needle points to the Earth’s Geographic North Pole because it is attracted to the Earth’s Magnetic North Pole.”
Answer:
Error: It is attracted to the Earth’s Magnetic North Pole.

Correction: A magnetic compass needle points to the Earth’s Geographic North Pole because its North pole is attracted to the Earth’s Magnetic South Pole, which is located near the Geographic North Pole.

Question 10.
Find and correct the error in this statement:
“To make a permanent magnet, I will wrap an insulated wire around a soft iron rod and connect it to a battery.”
Answer:
Error: Using a soft iron rod.
Correction: To make a permanent magnet, you should wrap the wire around a steel rod, not soft iron. (Soft iron would create a temporary electromagnet

Question 11.
Find and correct the error in this statement:
“Magnetic field lines are imaginary lines that show the direction of magnetic force. They start at the South pole and end at the North pole.”
Answer:
Error: They start at the South pole and end at the North pole.
Correction: Outside the magnet, magnetic field lines are directed from the North pole to the South pole.

Question 12.
Why is repulsion, and not attraction, considered the sure test for magnetism?
Answer:
Repulsion only occurs between two like poles (N-N or S-S) of magnets. Attraction, however, can occur in two different situations:

1. Between two unlike poles (N-S).
2. Between a magnet and an unmagnetized magnetic substance (like an iron nail) due to magnetic induction. Since attraction is not unique to two magnets, only repulsion can definitively prove that both objects are magnets.

Question 13.
Why will a freely suspended bar magnet always align itself in a North-South direction?
Answer:
This happens because the Earth itself acts like a giant magnet, with its own magnetic poles and magnetic field. The North pole of the bar magnet is attracted to the Earth’s Magnetic South Pole (which is located near the Geographic North Pole), and the magnet’s South pole is attracted to the Earth’s Magnetic North Pole. This alignment guides the magnet.

Question 14.
If you place a magnetic compass inside a box made of soft iron, it will not show the correct North-South direction. Why?
Answer:
This is due to magnetic shielding. Soft iron has a very high permeability, meaning it allows magnetic field lines to pass through it very easily. The soft iron box will “absorb” the Earth’s magnetic field lines, guiding them through its walls. This prevents the field lines from reaching the compass needle inside, so the needle cannot align with the Earth’s magnetic field.

Question 15.
A bar magnet (AB) with pole A as North and pole B as South is placed near an iron rod (CD) as shown in the assessment question.
a) What magnetic pole is induced at end C?
b) What magnetic pole is induced at end D?
c) What is this phenomenon called?
Answer:
a) The pole B (South) is near end C.
By induction, the nearer end gets the opposite pole. Therefore, C be comes a North pole.
b) The farther end D gets the like pole. Therefore, D becomes a South pole.
c) This phenomenon is called Magnetic Induction

Question 16.
You are given two identical-looking steel bars. One is a permanent magnet, and the other is just a plain steel bar. How can you identify which is the magnet without using any other object (like a compass or a third bar)?
Answer:

1. Hold one bar (Bar A) in your hand.
2. Bring one end of the second bar (Bar B) and touch it to the center of Bar A. Note the force.
3. Now, touch the same end of Bar B to one of the ends of Bar A.
4. Repeat this by trying to pick up Bar B with Bar A.
5. Observation: A magnet’s strength is strongest at the poles and very weak (almost zero) at its center. The unmagnetized steel bar has uniform properties.
6. Conclusion: The bar that can attract the other bar at its ends but cannot attract it (or attracts very weakly) at its center is the permanent magnet. The other bar is the plain steel bar.

Question 17.
You are given a hacksaw blade, a strong bar magnet, and some iron filings. Describe the procedure to:
a) Magnetise the hacksaw blade.
b) Confirm that the blade has been magnetized and identify its poles.
Answer:
a) Magnetisation (Single-Touch Method):

1. Place the hacksaw blade flat on a table.
2. Take the bar magnet and pick one pole (e.g., the North pole).
3. Press this pole down at one end of the blade (End A).
4. Rub the magnet along the blade to the other end (End B) in one continuous stroke.
5. Lift the magnet and bring it back to End A.
6. Repeat this process 20-30 times, always moving in the same direction (A to B) and using the same pole.

b) Confirmation:

1. Dip the newly magnetized blade into the pile of iron filings.
2. If it is magnetized, the iron filings will stick to it, especially at the ends (poles).
3. (To identify poles, you would need a compass or a known magnet, as the filings only show the presence of poles, not their N/S identity).

Question 18.
Describe an experiment to make a simple electromagnet and test its properties.
Answer:
Experiment:
Making: Take a soft iron nail and a long piece of insulated copper wire. Wind the wire tightly around the nail many times to form a coil.
Testing (OIM): Connect the free ends of the wire to the terminals of a battery. Bring the tip of the nail near a pile of paper clips.
Observation 1: The nail attracts the paper clips, proving it is now a magnet.
Testing (OFF): Disconnect one end of the wire from the battery.
Observation 2: The paper clips fall off the nail.
Conclusion: This shows that a mag¬net can be created with electricity, and it is a temporary magnet (an electromagnet) that only works when current is flowing.

Question 19.
Describe a procedure to draw the magnetic field lines of a bar magnet using a magnetic compass and a piece of paper.
Answer:

1. Place a white paper on a flat surface and fix it.
2. Place a bar magnet at the center of the paper and trace its outline. Mark the N and S poles.
3. Place a magnetic compass near the North pole (N).
4. Put a small dot on the paper at the exact point where the north tip of the compass needle is pointing.
5. Move the compass so that its south tip is now at the dot you just marked.
6. Put a new dot where the north tip is pointing now.
7. Repeat this “dot-to-dot” process. The compass will trace a curved path.
8. Continue until you reach the South pole (S) of the magnet.
9. Join all the dots to form a smooth curve. This is one magnetic field line.
10. Add an arrow to this line, pointing from North to South, to show its direction.
11. Repeat the entire process starting from a different point near the North pole to draw more field lines.

Question 20.
Name the following magnet.

Answer:
Bar magnet, Magnetic needle, U mag-net, Ring magnet, disc Meignetic

Question 21.
Which instrument is used to identify the direction in ship journey in ancient time?
Answer:
Compass

Question 22.
A bar magnet is hanged by a thread. Where does the north pole of the magnet point?
Answer:
The north pole of the compass points towards north of the earth that is south pole of earth’s magnet because earth is a magnet.

Question 23.
Write the magnetic substances from the following.
Wooden block, iron nail, paper, nickel, gold, cobalt, aluminium
Answer:
Iron nail, nickel, cobalt

Question 24.
Write the right statement
Greater susceptibility (Soft iron/ Steel)
Greater retentivity? (Soft iron/Steel)
Answer:
a. Soft iron b. Steel

Question 25.
Write three method to increase the strength of an electromagnet.
Answer:

1. The number of turns of coiled conductor
2. the strength of current
3. the area of cross section of the soft iron placed inside the coil.

Question 26.
You are given a bar magnet. The poles are not marked on it. Suggest a method to identify the poles of the magnet.
Answer:
The magnet is suspended using a thread so that it can oscillate freely in a horizontal plane. When it comes to rest the end pointing south can be marked as south pole.

Question 27.
A magnet is dipped in iron filing, the iron fillings are more attracted towards the poles of the magnet than towards other places. Why?
Answer:
The intensity at the poles is greater than that at other places.

Question 28.
North of geomagnet inclined against 110 with geoscientific north pole? Examine the statement.
Answer:
The statement is incorrect. North of geomagnet inclined against 11o with geoscienfic south pole. Magnet suspended on geomagnet alinged south – north direction is due to the attraction of unlike poles. North pole (N) of magnet attracted towards the south pole of geomagnet.

Question 29.
What are the difference in the magnetic properties of iron and steel?
Answer:
Iron becomes a more intense magnet on magnetic induction. But that magnetic power is temporary. When the permanent magnet is removed it losses its magnetic power. In the presence of a magnet, steel doesn’t acquire the magnetic power like that of a soft iron. But steel retains most of its magnetic power after removing the permanent magnet.

Question 30.
Write your inferences.
a. All magnets have same shape.
b. All magnets show N, S direction when suspended freely.
c. All magnets are man made.
d. All magnets show N, S direction when suspended freely.
Answer:
a. No, There are different types of magnets.
b. Yes, Because the north pole of magnet turns to geographical south of earth and south pole turns to geographical north of earth.
c. No, There are natural and man made magnets.
d. Yes.Earth acts like a large magnet. Hence the poles of the suspended magnet is opposite to the poles of the earth’s magnet.

Question 31.
When an iron nail is wounded with copper wire and connected to a battery, it doesn’t become a magnet, select the reasons from the following.
a. Battery has not enough charge.
b. The insulation at the ends of the wire is not removed.
c. The nail is wounded with non insulated copper wire.
d. The polarity of the battery is changing.
Answer:
a. Battery has not enough charge, b. The insulation at the ends of the wire is not removed, c. The nail is wounded with non insulated copper wire.

Question 32.
An Iron nail is suspended at the north pole of a bar magnet. Bring the north pole of another magnet near the free end of a nail. What is observed? What is its reason?
Answer:
The free end of an iron nail repel. Because the free end of an iron nail becomes north pole by magnetic induction.

Question 33.
Complete the figure

Answer:

Question 34.
The pole of a magnet attracts an iron nail which has no magnetic power. Describe the working behind this.
Answer:
The magnet attracts the iron nail brought near the pole of a magnet really as the result of magnetic induction. If the magnetic material reaches near the magnetic field of the magnet, an unlike pole is induced at its near end. The pole of permanent magnet is attract the newly formed unlike poles. That is why the magnetic pole attracts a magnetic material near it.

Question 35.
What are the factors that the attractive force of two magnetic poles depend on?
Answer:
The attractive force between the magnetic poles increases with increase in the strength of the pole and decreases with increase in the distance between the poles.

Question 36.
What is meant by atomic magnets?
Answer:
Each atom of a magnetic substance is an independent magnet. They are called atomic magnets.

Question 37.
What is meant by line of force (line of flux)?
Answer:
The line of force is the path that the north pole of a free magnetic needle would take around the bar magnet.

Question 38.
Examine the figure and mark the poles

Answer:

Question 39.
Which among the following statements is correct?
a) Like poles attracts each other.
b) Magnetic field is experienced in all directions around a magnet.
c) The direction of magnetic lines of force is from the north pole outside the magnet.
Answer:
b)Magnetic field is experienced in all directions around a magnet.

Question 40.
In the figure, south poles of two bar magnets are placed facing one another. Redraw the figure and illustrate magnetic field lines?

Answer:

Question 41.
Which of the following has more susceptibility.”(Steel / Soft iron)
Answer:
Soft iron

Question 42.
The following figures depict, two electromagnets made from two iron nails of same size. Which is the strongest electromagnet?

Answer:
a)

Question 43.
a) Draw magnetic lines of force between the given poles of magnets.

b) Write any two peculiarities of magnetic lines of force.
Answer:
a)

b) i. Magnetic lines of force do not intersect one other
ii. Magnetic lines of a force are from north pole to south pole

Question 44.
A magnetic needle is suspended so as to move freely in a horizontal plane.
a. In which direction north pole of the magnetic needle is pointing.
b. Give reason for it.
c. The case of magnetic compass is not made of soft iron? Why?
Answer:
a. The north pole of a bar magnet pointing towards the geographic north when it suspended freely.

b. The earth itself acts like a magnet. Just as the earth has north and south geographically the earth has north and south geographically. It has the north pole and the south pole when considered as a magnet. The south pole of the earth’s magnet is near the geographic north and the north pole of the earth’s magnet is near the geographic south. Hence the freely suspended magnet pointing towards the geographic north.

c. Magnetic lines of force pass more easily through soft iron than through the air. This ability is called as permeability. Hence the magnetic lines of forces from the magnetic needle spread into the iron case and the needle loses its directional property. So the case of magnetic compass is not made of soft iron core.

Question 45.
Select the correct statement.
a. The north pole of the earth’s magnet is near the geographic north pole.
b. The south pole of the earth’s magnet is near the geographic north pole.
c. The south pole of the earth’s magnet is at the equator.
Answer:
b.The south pole of the earth’s magnet is near the geographic north pole.

Question 46.
A magnetised hacksaw blade is cut into pieces as shown in figure.

a. Find the polarity of the edges B and D.
b. Suggest a method to make the hacksaw blade into a permanent magnet.
Answer:
a. B-North D – North

b. Place the hacksaw blade on a table. Rub the north pole of the bar mag-net NS starting from one end to the another end of the blade. Repeat it several times in the same manner. The hacksaw blade will change into a magnet.

Question 47.
An iron rod and a steel rod of equal size are placed near a magnet. Complete the following table based on the property of these substances.

Which rod act as a stronger magnet	…………… a …………..
Which rod retains the magnetic powder even after removed it from the magnet	…………… b …………..

Answer:
a. Iron rod
b. Steel rod

Question 48.
A and B are two magnetic materials. Analyse their properties and answer the questions.
i. A is easily magnetised compared to B than that for A.
ii. Ability to retain the magnetism thus acquired is more for B than that for A
a. Which these is the most suitable material for making a permanent magnet? Explain why?
b. Write the name of a substance used for making permanent magnets.
Answer:
a. B is the suitable material used to make permanent magnet. Because it has retentivity or it has the ability retain the acquired magnetic strength.

b. Steel, Alnico

Question 49.
The magnetic flux lines between two
magnetic poles are drawn in the figure.

a. Name the poles represented by A and B.
A. ……………………… B. …………………………….
b. Give the principle helped you to write down this answer
Answer:
a. A – South, B – North
b. The direction of magnetic lines of force is from the north pole to the south pole.

Question 50.
Which of the following is the correct picture?

Answer:
c

Question 51.
a. Which are the materials required to make an electromagnet
b. Using these materials, how can you make an electromagnet?
c. Suggest a method to increase the strength of an electromagnet?
Answer:
a. Insulated copper wire, soft iron piece.
b. By passing electric current through insulated copper wire wound on a so¬ft iron piece.
c. By increasing the number of turns of wire in the coil

Question 52.
Which of the following is an example of a natural magnet?
A. Alnico magnet
B. Horseshoe magnet
C. Lodestone
D. Electromagnet
Answer:
C. Lodestone

Question 53.
What is the directional property of a freely suspended magnet?
A. It aligns itself East-West.
B. It aligns itself North-South.
C. It points towards the nearest metal object.
D. It always points towards the sun.
Answer:
B. It aligns itself North-South.

Question 54.
Which pair of magnetic poles will exhibit the strongest force of repulsion?
A. North pole (N) and South pole (S)
B. North pole (N) and North pole (N)
C. South pole (S) and South pole (S)
D. Both B and C
Answer:
D. Both B and C

Question 55.
Where is the Earth’s Magnetic South Pole located?
A. Exactly at the Geographic South Pole.
B. Near the Geographic South Pole.
C. Near the Geographic North Pole.
D. Exactly at the Equator.
Answer:
C. Near the Geographic North Pole.

Question 56.
What does the high density of magnetic field lines in a specific region indicate?
A. The magnetic field is weakest in that region.
B. The region is non-magnetic.
C. The magnetic field is strongest in that region.
D. The magnetic field lines are intersecting.
Answer:
C. The magnetic field is strongest in that region.

Question 57.
Explain the rule for attraction and repulsion between magnetic poles. Give one application of this principle.
Answer:
Rule for Attraction and Repulsion:
Attraction: Unlike poles attract each other (North attracts South).
Repulsion: Like poles repel each other (North repels North, and South repels South).
Application: This principle is used in Magnetic Levitation (Maglev) technology, where the repulsion between like poles is used to lift a train above the track, eliminating friction.

Question 58.
Describe the composition of two types of artificial magnets mentioned in the chapter.
Answer:
Composition of Artificial Magnets: Alnico Magnets: These are strong metal alloys made from Aluminum, Nickel, Cobalt, and Iron (Fe).
Ceramic/Ferrite Magnets: These are made by mixing iron oxide with carbonates of elements like barium or strontium.

Question 59.
State two essential characteristics of magnetic field lines. How does the “SingleTouch Method” of magnetisation work, and what pole is acquired at the starting end of the unmagnetised material?
Answer:
Characteristics of Magnetic Field Lines:

• Closed Loops: Magnetic field lines form continuous, closed loops. They emerge from the North pole and enter the South pole outside the magnet, and continue from South to North inside the magnet.
• Non-Intersecting: They never intersect (cross) each other. If they did, it would mean that at the point of intersection, a compass needle would point in two different directions simultaneously, which is impossible.
• (Note: Stating the direction (N to S outside the magnet) is also a valid characteristic.)
• Single-Touch Method and Pole Acquisition:
• The Single-Touch Method involves repeatedly stroking an unmagnetised material (like a steel bar) in a single, consistent direction using one pole of a permanent magnet.
• The pole acquired at the starting end of the steel bar will be the opposite pole to the one used for rubbing. For example, if you rub the bar starting from end A using a North pole, end A will acquire a South pole.

Question 60.
What is a magnetic field, and where is the field strength typically the strongest on a bar magnet?
Answer:
A magnetic field is the region of space surrounding a magnet where its magnetic force can be experienced by another magnetic material or magnet. The magnetic field strength is typically the strongest at the poles (the North and South ends) of the bar mag¬net, where the magnetic field lines are densest.

Question 61.
Explain the difference between natural and artificial magnets, and give one example for each type, including the specific composition for the artificial magnet example.
Answer:
Natural Magnets
Definition: Magnets that are obtained directly from nature.
Purpose: Used as they are found. Example: Lodestone (mineral name: Magnetite).
Artificial Magnets
Definition: Magnets that are man-made using various metallic alloys.
Purpose: Made in specific shapes, sizes, and strengths as needed by humans.
Example: Alnico Magnets: These are alloys primarily made from Aluminum (Al), Nickel (Ni), Cobalt (Co), and Iron (Fe).

The comprehensive approach in SCERT Class 8 Basic Science Textbook Solutions Chapter 10 Static Electricity Important Questions ensure conceptual clarity.

Static Electricity Extra Questions and Answers Class 8 Basic Science Chapter 10 Kerala Syllabus

Static Electricity Class 8 Important Questions

Question 1.
Which of the following devices is used to detect the presence of an electric charge?
a) Capacitor
b) Electroscope
c) Lightning Arrester
d) Voltmeter
Answer:
b) Electroscope

Question 2.
The safe transfer of charge from an object to the Earth is called:
a) Conduction
b) Induction
c) Earthing
d) Repulsion
Answer:
c) Earthing

Question 3.
When a glass rod is rubbed with silk, the glass rod becomes positively charged. This is because:
a) It gains protons
b) It gains electrons
c) It loses protons
d) It loses electrons
Answer:
(d) It loses electrons

Question 4.
Statement 1: Like charges attract each other, and unlike charges repel each other.
Statement 2: Repulsion is the surest test for electrification (charging).
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
c) Only Statement 2 is correct.

Question 5.
Statement 1: A lightning conductor protects a building by providing a safe path for the lightning’s charge to flow to the Earth.
Statement 2: The top of a lightning conductor is made sharp because charges accumulate and discharge more easily from sharp points.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
a) Both statements are correct.

Question 6.
Statement 1: In charging by conduction, the object being charged gets the same charge as the charging object.
Statement 2: In charging by induction, the object being charged gets the same charge as the charging object.
a) Both statements are correct.
b) Only Statement 1 is correct.
c) Only Statement 2 is correct.
d) Both statements are incorrect.
Answer:
b) Only Statement 1 is correct. (Statement 2 is incorrect; induction gives the opposite charge).

Question 7.
Classify the following materials into Conductors and Insulators:
(Copper, Plastic, Rubber, Silver, Dry Air, Glass, Iron)
Answer:
Conductors: Copper, Silver, Iron
Insulators: Plastic, Rubber, Dry Air, Glass

Question 8.
Categorize the following phenomena as examples of Attraction or Repulsion:
a) A positively charged rod brought near a negatively charged rod.
b) Two balloons rubbed with the same piece of wool brought near each other.
c) A charged balloon sticking to a neutral wall.
d) The leaves of a charged electro scope moving apart.
Answer:
a) Attraction
b) Repulsion
c) Attraction
d) Repulsion

Question 9.
Complete the table related to charging methods:

Method	Physical Contact? (Yes/No)	Charge Gained (Same/Opposite)
Conduction	……….(a)……..	………(b)………
Induction	………(c)………	………(d)………

Answer:
a) Yes
b) Same
c) No
d) Opposite

Question 10.
A student wrote down the following statements. Find the incorrect one(s) and correct them.
a) An atom is neutral because it has no charge.
b) A negatively charged object has an excess of electrons.
c) Protons are transferred when charging by friction.
Answer:
a) Incorrect. Correction: An atom is neutral because it has an equal number of positive protons and negative electrons.

c) Incorrect. Correction: Electrons are transferred when charging by friction.

Question 11.
Find and correct the error in this statement about earthing:
“When a positively charged object is earthed, the positive charges (protons) flow from the object into the Earth.”
Answer:
Error: Protons do not flow.
Correction: When a positively charged object is earthed, electrons flow from the Earth into the object to neutralize it.

Question 12.
A student’s notes on an electroscope are given. Find the mistake and correct it.
“An electroscope is a device used to store electric charge. Its ability to store charge is called capacitance.”
Answer:
Error: This is the definition of a capacitor.
Correction: An electroscope is a device used to detect the presence of electric charge.

Question 13.
A plastic comb rubbed on dry hair can attract small pieces of paper. Why does this happen?
Answer:
When the comb is rubbed on hair, friction causes electrons to transfer from the hair to the comb. The comb becomes negatively charged. This charged comb then attracts the neutral pieces of paper through electrostatic induction (by polarizing the charges in the paper).

Question 14.
Why is it more dangerous to stand under a tall, isolated tree during a thunderstorm?
Answer:
During a thunderstorm, a charged cloud passes overhead. It induces an opposite charge on the ground below. Since a tall tree is the closest point to the cloud and charge accumulates at points, it becomes a prime target for a lightning strike. The lightning will take the easiest path to the ground, which is through the tree.

Question 15.
Why do technicians repairing mobile phones or computers often wear anti-static wrist straps or gloves?
Answer:
The human body can easily build up a static charge. The components inside a mobile phone or computer are extremely sensitive. If a technician touches these components, a static discharge (a tiny spark) can occur, permanently damaging the electronic circuits. The anti-static gear safely earths the technician, preventing any charge from building up.

Question 16.
An atom of Sodium (Na) has 11 protons and 11 electrons.
a) What is the total charge of the atom?
b) If this atom loses one electron, what will be its new charge?
Answer:
a) The total charge is zero (0), or neutral, because the 11 positive protons cancel out the 11 negative electrons.

b) It will have 11 protons (+11) and 10 electrons (-10). The new charge will be +1 (positively charged).

Question 17.
A metal sphere (A) has a charge of -12 units. An identical metal sphere (B) has a charge of +4 units. If the two spheres are touched together and then separated, what will be the final charge on each sphere? Answer:
Total Charge: (-12) + (+4) = -8 units.
When touched, this total charge is shared equally.
Final Charge on Each: -8 / 2 = -4 on sphere A and -4 units on sphere B.

Question 18.
An atom of Chlorine (Cl) has 17 protons.
a) How many electrons does a neutral Chlorine atom have?
b) If this atom gains one electron, what will its charge be?
Answer:
a) A neutral atom must have an equal number of electrons and protons, so it has 17 electrons.
b) It will have 17 protons (+17) and 18 electrons (-18). The new charge will be -1 (negatively charged).

Question 19.
You are given a metal sphere on an insulating stand. Describe the steps to give this sphere a permanent positive charge using the method of induction.
Answer:

1. Step 1: Bring a negatively charged rod (e.g., an ebonite rod rubbed with wool) near the metal sphere, without touching it.
2. Step 2: The free electrons in the sphere are repelled by the rod and move to the far side of the sphere. The side near the rod becomes positively charged.
3. Step 3: While the negative rod is still held nearby, touch the far side of the sphere with your finger. This earths the sphere.
4. Step 4: The repelled electrons now have a path to escape and will flow from the sphere, through your body, and into the Earth.
5. Step 5: Remove your finger first (breaking the earth connection).
6. Step 6: Finally, remove the negative rod. The sphere is now left with a deficit of electrons, giving it a permanent positive charge that spreads evenly over its surface.

Question 20.
You are given a charged rod, but you don’t know if it is positive ‘or’ negative. Describe how you could use an electroscope to find out the sign of the charge.
Answer:

1. Step 1: First, charge the electroscope with a known charge. For example, touch it with a glass rod rubbed with silk. The electroscope is now positively charged, and its leaves will be diverged.
2. Step 2: Bring the unknown charged rod near (do not touch) the metal disc at the top of the charged electroscope.
3. Step 3: (Observe): If the leaves diverge (move further apart): The unknown rod has the same charge as the electroscope. It is positive. (It repels more positive charges down to the leaves).
   If the leaves converge (move closer together): The unknown rod has the opposite charge. It is negative. (It attracts the positive charges from the leaves up towards the disc).

Question 21.
Describe the steps to charge a metal sphere using charging by conduction to give it a negative charge.
Answer:

1. Step 1: Obtain an object that is negatively charged, (e.g., a plastic pen rubbed on dry hair or an ebonite rod rubbed with wool).
2. Step 2: Bring this negatively charged object and touch it directly to the neutral metal sphere.
3. Step 3: When they touch, some of the excess electrons from the charged object will flow onto the neutral sphere, sharing the charge.
4. Step 4: Remove the charging object. The sphere now has an excess of electrons and is permanently negatively charged.

Question 22.
Complete the table

Objects	Electron exchange	Positive	Negative
Glass, silk	From glass rod to silk	………..a………..	Silk
Ebonite, wool	Wool to ebonite	………..b………..	………..c………..
Rubber rod, wool	………..d………..	Wool	………..e………..

Answer:
a. Glass
b. Wool
c. Ebonite
d. From wool to rubber rod
e. Rubber rod

Question 23.
When a glass rod is rub with silk electron loses from the glass rod. If we bring another glass rod near to it what can be observed? Give reason
Answer:
They will repel. Same charges repel each other.

Question 24.
Tick the correct one
1. Object with same charge attract/repel
2. The charged body attract/repel the neutral body
3. bodies with different charges attract/repel.
Answer:
1. repel
2. attract
3. attract

Question 25.
What is the use of capacitor?
Answer:
To store the charge

Question 26.
What is earthing?
Answer:
Connecting an object to earth with a conductor is called earthing.

Question 27.
Examine the following figures and mark the point which charge is accumulated.

Answer:

Question 28.
Complete the figure.

Answer:

Question 29.
Why does the pointed edged conductors are used as lightning conductor
Answer:
The charge accumulated at the pointed edge easily and discharge it to earth immediately. So the building is not effected by lightning

Question 30.
What are the precautions to be taken when lightning
Answer:

• Do not operate electrical equipments
• Do not lay on the wall of the house.
• Do not stand holding windows bar or grill
• Do not stand beneath tall trees
• Do not take shelter under isolated trees

Question 31.
What are the primary steps to be adopted when a person is struck by lightning
Answer:
A person struck by lightning should be made to lie in a place where there is good air circulation. In order to prevent blood clotting keep the body warm by massaging. Give artificial respiration and press strongly on the chest to maintain heart beat and the person must be taken to a hospital immediately

Question 32.
What is dielectric
Answer:
The dielectric are the insulators used in between the plates of the capacitor to increase its capacity Eg. Plastic, polyester, air, paper

Question 33.
What is capacitance. What is its unit
Answer:
capacitance is the ability to store the charge in it. Its unit is fared(F).
1 F = 10⁶ μF(microfared)
1 F = 10¹² pF (picofarad)

Question 34.
You might have seen iron chains, suspended from the body of lorries and trucks touching the earth. What is this for?
Answer:
These lorries and trucks have to travel a long distance. Sometimes the friction between rod and tyre or vehicle and oil in it produces static electricity. This discharge gathers at one end of the truck and it causes sparking and from it the petrol may catch fire. The iron chains suspended from the body of lorries and trucks provide earthing and help to avoid the hazard.

Question 35.
The installation of lightning conductors is not insisted in may tall modern concrete buildings, now-a-days. How are they protected from lightning?
Answer:
In tall modern buildings, there are plenty of metal rods inside the concrete work, connecting from the top to bottom of the building and to the earth. Electric charge from the lightning clouds, reaching the building, is conducted safely to the earth through these metal rods. So the building are protected from damage due to lightning discharge.

Question 36.
A person takes shelter under a tree during heavy rain. Another person shelters under a coconut tree of same height. Who will be safer during lightning? Why?
Answer:
The person standing under the tree is more safe. Electric charge always get concentrated at sharp edges. So more possibility for danger due to lightning is to the man under coconut tree than the other one.

Question 37.
There are two houses nearby, both of them having T.V. antenna pipes. One of these pipes is earthed. Write down the advantages or disadvantages of earthing the pipe.
Answer:
Advantage
When lightning strikes the antenna it does not affect the house if the antenna pipe is earthed. The electric charge of the lightning goes to the earth through the pipe and so it acts as a lightning conductor.

Question 38.
An ebonite rod is rubbed against a piece of wool.
a. What is the electric charge gained by the ebonite rod?
b. If the charged ebonite rod is earthed, electron transfer will be from.
i) ebonite rod to the earth.
ii) the earth to ebonite rod.
Answer:
a. Negative charge
b. i OR ebonite rod to earth.

Question 39.
Observe the picture.

a. Identify the device.
b. Write its use.
c. If a negatively charged object is brought near the metal sphere of the device, what will be the charge acquired on.
i) the metal sphere?
ii) the metal leaves?
Answer:
a. Electroscope
b. To identify and understand the nature of electric charge.
c. (i) Positive (ii) Negative

Question 40.
What happens when two objects carrying a like charge are brought near each other?
a) They attract.
b) They repel.
c) They become neutral.
d) No interaction occurs.
Answer:
b) They repel.

Question 41.
An object that gains electrons through friction acquires what type of charge?
a) Positive charge
b) Negative charge
c) Neutral charge
d) Variable charge
Answer:
b) Negative charge

Question 42.
Which of the following methods is used to charge a conductor with the opposite charge without touching it?
a) Charging by Conduction
b) Charging by Friction
c) Charging by Induction
d) Charging by Direct Contact
Answer:
c) Charging by Induction

Question 43.
Why can a plastic pen be charged by rubbing, but a steel spoon cannot (when held by hand)?
a) Steel is an insulator,
b) Plastic is a better conductor than steel.
c) Steel is a conductor, and the charge flows away through the hand.
d) Plastic has a smaller surface area.
Answer:
c) Steel is a conductor, and the charge flows away through the hand.

Question 44.
What is the primary function of Earthing a charged object?
a) To increase the charge on the object.
b) To provide a safe path for charge to flow to or from the Earth, thereby neutralizing the object.
c) To convert static electricity into current electricity.
d) To store the charge permanently.
Answer:
b) To provide a safe path for charge to flow to or from the Earth, thereby neutralizing the object.

Question 45.
In the context of the Electrostatic Spray Painting application:
a) What charge is given to the paint droplets?
b) Why does the paint stick to the vehicle body?
Answer:
a) Negative charge (-).

b)The paint droplets are negatively charged, and the vehicle body is positively charged. Unlike charges attract, causing the paint to stick strongly and evenly to the surface.

Question 46.
Explain why a gold-leaf Electroscope is a better device for detecting the presence of an electric charge than simply trying to observe attraction to a neutral object.
Answer:
Repulsion is the surest test for electric charge.

• If an object attracts another object, the second object might be charged (opposite charge) or it might be neutral.
• If the leaves of an electroscope repel (diverge), it confirms that the incoming object has successfully charged the leaves (like charge), proving it is charged.

Question 47.
An aluminum sphere is positively charged. Explain briefly how it gets neutralized when it is connected to the Earth (earthed).
Answer:
A positively charged object has a deficiency of electrons. When earthed:

• Electrons flow from the Earth to the object.
• These electrons fill the deficit, and the object’s charge becomes neutral.

Question 48.
Explain the purpose of using a Lightning Conductor on a tall building. Describe itstwo main functions when a charged cloud passes over.
Answer:
Purpose: To protect the building from structural damage, fire, and explosions caused by a massive lightning strike.

• Function 1 (Charge Neutralization): The sharp points induce the opposite charge from the cloud, allowing some gradual discharge to neutralize the cloud’s charge accumulation.
• Function 2 (Safe Path): If lightning strikes, the conductor provides a safe, low-resistance path for the massive electric current to flow directly into the ground, completely bypassing and protecting the building.

Question 49.
A positively charged glass rod is used to charge a neutral metal sphere by induction. Describe the three essential steps required to leave the sphere with a permanent negative charge.
Answer:
Target: Permanent Negative charge using a Positively charged rod.

1. Induction: Bring the positively charged rod near the neutral sphere. (Positive rod attracts electrons to the near side and repels positive charge to the far side).
2. Earthing: While the rod is held in place, connect the sphere to the ground. (Repelled positive charge is neutralized as electrons flow up from the Earth).
3. Isolation & Removal: Remove the earthing connection first, and then remove the rod. (The excess electrons are trapped and redistribute, leaving the sphere permanently negatively charged).

Question 50.
Why are the nozzles used for filling petrol at petrol pumps mandatorily earthed?
Explain the concept of static electricity involved.
Answer:
Concept: The process involves protecting against Electrostatic Discharge (ESD).

Static Build-up: The rapid flow of petrol through pipes and the nozzle creates friction, generating a large static electric charge on the equipment.

Danger: Petrol fumes are highly flammable. If the static charge built up is suddenly discharged (a spark) to the vehicle or ground, it will ignite the fumes, causing a fire or explosion.

Earthing Solution: The earthing connection provides a safe path for any accumulated static charge to continuously flow away into the Earth, ensuring no dangerous sparks can occur during filling.

Parents often use SCERT Kerala Syllabus 8th Standard English Notes Pdf Unit 5 Chapter 3 Village of the Watermills Questions and Answers Activities Notes to assist their kids with homework.

Class 8 English Village of the Watermills Question Answer Activities

Village of the Watermills Questions and Answers Class 8

8th Standard English Village of the Watermills Question Answer 

Question 1.
Whom does the young man see near the wooden mills? What was the person doing?
തടി മില്ലുകൾക്ക് സമീപം യുവാവ് ആരെയാണ് കാണുന്നത്? ആ വ്യക്തി എന്തു ചെയ്യുകയായി രുന്നു?
Answer:
Near the wooden mills, the young man sees an old man with grey hair wearing a hat. The old man was adjusting the large gears of the water mill.

Question 2.
What does the old man think of modern conveniences like electricity? Can we think of living without electricity now?
വൈദ്യുതി പോലുള്ള ആധുനിക സൗകര്യങ്ങ ളെക്കുറിച്ച് വൃദ്ധൻ എന്താണ് കരുതുന്നത്? ന മുക്ക് ഇപ്പോൾ
വൈദ്യുതിയില്ലാതെ ജീവിക്കു ന്നതിനെക്കുറിച്ച് ചിന്തിക്കാൻ കഴിയുമോ
Answer:
The old man thinks modern conveniences like electricity are unnecessary (“we don’t need it”). He feels people are too used to them and that they “throw out what is truly good” by always seeking the easier way.

(Personal Reflection) Nowadays, it is extremely difficult for most people to think of living without electricity. Our entire modern life-lighting, communication, work, entertainment, health-care, and transportation-relies heavily on it. While possible in certain remote or chosen lifestyles, it’s not practical for the vast majority.

Question 3.
The villagers use firewood and dung as fuel. What kinds of fuel do we use now?
ഗ്രാമീണർ വിറകും ചാണകവുമാണ് ഇന്ധമായി ഉപയോഗിക്കുന്നത്. നമ്മൾ ഇപ്പോൾ ഏത് തര ത്തിലുള്ള ഇന്ധനങ്ങളാണ് ഉപയോഗിക്കുന്നത്?
Answer:
The villagers primarily use firewood and dung as fuel. In contrast, we now predominantly use fuels like LPG (cooking gas), electricity, petrol, diesel, CNG (Compressed Natural Gas), kerosene, and increasingly, solar energy.

Question 4.
Describe the old man’s appearance when he comes out of the wooden house.
തടിവീട്ടിൽ നിന്ന് പുറത്തുവരുമ്പോൾ വൃദ്ധ ന്റെ രൂപം വിവരിക്കുക.
Answer:
When the old man comes out of the wooden house to join the funeral procession, he is wearing a colourful dress and a hat, and he carries a pair of Shinto bells in his hand.

Question 5.
How old is the old man? What, according to you, keeps the old man active and healthy even at his age?
വൃദ്ധന് എത്ര വയസ്സുണ്ട്? നിങ്ങളുടെ അഭിപ്രാ യത്തിൽ, ഈ പ്രായത്തിലും വൃദ്ധനെ സജീ വവും ആരോഗ്യവാനുമായി നിലനിർത്തുന്നത് എന്താണ്?
Answer:
The old man is one hundred and three years old. According to me, several factors likely keep him active and healthy:

• Natural Lifestyle: Living close to nature, breathing clean air, drinking clean water, and eating simple food.
• Physical Activity: Engaging in daily work like adjusting the watermill gears keeps him physically active.
• Positive Outlook: He finds life “exciting” and seems content with his simple existence.
• Strong Community: Living within a supportive community might contribute to his well-being.

Village of the Watermills Questions and Answers – Let’s rewind

Question 1.
How is the village described? Would you like to live in a village or in the city? Why?
ഗ്രാമത്തെ എങ്ങനെയാണ് വർണ്ണിച്ചിരിക്കു ന്നത്? നിങ്ങൾക്ക് ഗ്രാമത്തിലാണോ നഗരത്തി ലാണോ ജീവിക്കാൻ ഇഷ്ടം? എന്തുകൊണ്ട്?
Answer:
The village is described as a peaceful, picturesque place without electricity or modern conveniences. It has watermills, wooden bridges, and flowers along the riverbank. The villagers live a simple, natural life, using firewood and dung for fuel, and cows and horses instead of tractors. They seem content and live in harmony with nature.

Question 2.
How does the young man’s interaction with the villagers challenge his views on modernity and the modern lifestyle? What does this tell us about the value of cultural exchange?
ഗ്രാമീണരുമായുള്ള യുവാവിന്റെ സംഭാഷണം ആധുനികതയെയും ആധുനിക ജീവിതശൈലി യെയും കുറിച്ചുള്ള അവന്റെ കാഴ്ചപ്പാടുകളെ എങ്ങനെ ചോദ്യം ചെയ്യുന്നു? സാംസ്കാരിക വിനിമയത്തിന്റെ (cultural exchange) മൂല്യ ത്തെക്കുറിച്ച് ഇത് നമ്മോട് എന്താണ് പറയുന്നത്?
Answer:
The interaction challenges his views by showing him a completely different way of life that is fulfilling without modern technology. The old man questions the modern belief that ‘easier is better’ and points out the pollution caused by modern life. The young man is initially surprised and possibly skeptical (‘looks at the old man as if in disbelief’), but he also seems curious and perhaps thoughtful by the end. This tells us that cultural exchange is valuable because it exposes us to different perspectives, challenges our assumptions, and helps us appreciate diverse ways of living and thinking.

Question 3.
What is your opinion of the villagers’ notion of death as a cause for celebration rather than mourning?
മരണത്തെ ദുഃഖാചരണത്തിന് പകരം ആഘോ ഷത്തിനുള്ള കാരണമായി കാണുന്ന ഗ്രാമീണ രുടെ കാഴ്ചപ്പാടിനെക്കുറിച്ച് നിങ്ങളുടെ അഭി പ്രായമെന്താണ്?
Answer:
The villagers’ view of death as a celebration for those who lived long, hardworking lives is thought-provoking. It reflects their deep connection with the natural cycle of life and death. They see a long life lived well as something to be honored and celebrated. While mourning is a natural human emotion, their perspective offers a different way to approach death, focusing on gratitude for a completed life rather than solely on the sadness of loss. However, they also acknowledge that the death of the young is different and harder to celebrate.

Question 4.
What do the film’s visuals and sound effects reveal about the lifestyle of the villagers?
സിനിമയിലെ ദൃശ്യങ്ങളും ശബ്ദങ്ങളും ഗ്രാമീണ രുടെ ജീവിതശൈലിയെക്കുറിച്ച് എന്താണ് വെ ളിപ്പെടുത്തുന്നത്?
Answer:
The visuals (wide shots of the village, river, watermills, wooden bridge, flowers, trees) and sound effects (sound of water, cuckoo’s sound, jingling Shinto bells) reveal a simple, peaceful, and traditional lifestyle deeply connected to nature. The lack of sounds associated with modern technology (like cars or machinery) and the presence of natural sounds and visuals of traditional tools (watermills) emphasize their harmonious, eco-friendly way of life. The rhythmic movement and music of the funeral procession also suggest a strong sense of community and tradition.

Village of the Watermills Activities

Class 8 English Village of the Watermills Activities Pdf – Let’s recall and recreate:

Activity 1

Haven’t you noticed the different themes and the underlying ideas in the screenplay? Complete the table, nothing more themes/ideas.

കൂടുതൽ വിഷയങ്ങൾ ആശയങ്ങൾ രേഖപ്പെടുത്തി പട്ടിക പൂർത്തിയാക്കുക
Answer:

Theme	Explanation
Living in harmony with nature	The villagers follow eco friendly practices. Instead of cutting down living trees, they use dead trees for firewood. They live without electricity and modern conveniences, relying on natural resources.
Life and death	Life and death are portrayed as quite natural. Death and funerals (for the old) are seen as occasions to honour a person rather than to mourn them.
Tradition vs. Modernity	The screenplay contrasts the villagers’ traditional, nature-based lifestyle with the modern world’s reliance on technology and convenience. The old man criticizes the modern belief that ‘easier is better’.
Simplicity and Contentment	The villagers live a simple life without modern amenities but seem content and wise. They find value in their connection to nature and community traditions.
Environmental Concerns	The old man explicitly talks about pollution and how modern humans destroy the nature they depend on, highlighting environmental issues.

Class 8 English Village of the Watermills Question Answer – Activity 2

A. You have enjoyed reading the screenplay ‘Village of the Watermills’, haven’t you? Revisit the script and fill in the blanks.

Answer:
Title: Village of the Watermills
Writer/Film-maker: the film is often attributed to Akira Kuro sawa as part of his film “Dreams”

B. Now, write a paragraph on the theme, characters, setting, and other features of the film

Answer:
Setting:
[Where and when does the story take place? (location and time)]
A remote, timeless village in Japan, seemingly untouched by modernity, featuring watermills along a river. The time appears to be daytime during a pleasant season.

Characters:
[The major and minor characters and their roles]

• Young Man: An outsider, representing modernity, who visits the village and learns about its ways. The protagonist through whose eyes we see the village.
• Old Man: A wise, 103-year-old villager who acts as the guide and explains the village’s philosophy of life.
• Children/Villagers: Represent the community living in harmony with nature and tradition to be daytime during a pleasant season.

Opening shot / scene:
[What happens at the beginning of the film?]
A young man walks across a long wooden bridge into a village powered by watermills. He observes the scenery and interacts briefly with some children.

Climax and Resolution:
[The most intense, emotional moment in the film/how the conflict is resolved]
Climax and Resolution: [The most intense, emotional moment / how the conflict is resolved]

The climax is arguably the funeral procession, presented as a happy celebration. It encapsulates the village’s unique perspective on life and death. The resolution is the Young Man’s quiet acceptance and perhaps changed perspective, shown when he places flowers on the traveller’s stone and walks away thoughtfully.

Plot Development:
What are the key events that move the story forward?]

• places flowers on the traveller’s stone and walks away thoughtfully.
• Young Man arrives and observes the village.
• He meets the Old Man and inquires about the village’s lifestyle (no electricity, no tractors, use of natural fuel).
• The Old Man explains their philosophy of living naturally and criticizes modern pollution.
• They discuss the custom of placing flowers on the stone.
• They witness the ‘happy funeral’ procession.
• The Old Man reveals his age and positive outlook on life. The Young Man leaves, performing the village custom

Theme and message:
[What is the central idea? What does the film convey to you?]
The central theme is the contrast between a traditional, nature-harmonious lifestyle and modern, technology-driven life. The film conveys the message that simplicity, connection with nature, and community traditions hold profound value and wisdom that modernity often overlooks or destroys. It critiques pollution and the modern obsession with convenience.

B. Now, write a paragraph on the the me, characters, setting, and other features of the film.
ഇപ്പോൾ, സിനിമയുടെ വിഷയം, കഥാപാത ങ്ങൾ, പശ്ചാത്തലം, മറ്റ് സവിശേഷതകൾ എന്നിവയെക്കുറിച്ച് ഒരു ഖണ്ഡിക എഴുതുക.
Answer:
“Village of the Watermills” presents a serene setting-a seemingly timeless Japanese village untouched by modern technology, characterized by its picturesque riverbanks and functional watermills. The main characters are a curious Young Man, representing the modern world, and a wise, 103-year- old villager who embodies the village’s philosophy. Through their interaction, the film explores its central theme: the value of living in harmony with nature versus the pitfalls of modernity. The villagers’ rejection of electricity and tractors, their respect for natural resources, and their unique, celebratory approach to death for the elderly highlight a life of simplicity and contentment. Visually, the film uses peaceful imagery and natural sounds to reinforce the tranquility of this lifestyle, ultimately conveying a powerful mes- sage about environmental consciousness and the potential loss of wisdom in the relentless pursuit of modern convenience.

Activity 3

We now know that the script/screenplay is an essential part of a film, don’t we? There are a number of terms specific to the field of cinema. For instance, a shot in a film is a single, unbroken recording from the time the camera starts to when it stops.
Here are some other key terms in film terminology.

Now, look at the following pictures and identify the name of the shots

Answer:

Std 8 English Village of the Watermills Question Answer – Activity 4

The villagers in ‘Village of the Watermills’ do not make use of modern conveniences like electricity, or motor vehicles. They do not wish to depend on technology. What are your thoughts on this attitutde to life? Let’s conduct a debate on the topic:
Lifestyle Preferences: Rural vs Urban

Answer:

I prefer rural life because…	I prefer urban life because….
rural areas are less crowded, calm and quiet, and there is fresh air all around.	of the medical and other facilities, gyms, transport, etc.
in rural settings, people live close together and share emotional and social support.	there may be more opportunities for employment and economic growth in cities.
there is closer contact with nature and a slower pace of life	cities offer greater access to higher education, cultural events (museums, concerts), and diverse entertainment options
cost of living is generally lower in rural areas.	urban areas provide more diversity in terms of people, cultures, and cuisines.

Std 8 English Village of the Watermills Question Answer – Let’s play with words:

Activity 1

Question 1.
Read the following sentences from the story ‘A Tale of Two Gifts’.(Text book page no.156)
• Her eyes sparkled, but her face had lost its color.
• Something almost worth the honor of belonging to Jim.
Did you notice the spelling of the highlighted words?
Here, the words are spelt as in U.S./North American English.
In British English, these words are written as ‘honour’ and ‘colour’.

The table below lists some common English words that are spelt differently in
British and North American English. Complete it, and add more to the list.

Answer:

British English	U.S./N.AmericanEnglish
labour	labor
travelling	traveling
theatre	theater
jewellery	jewelry
programme	program
colour	color
honour	honor
analyse	analyze

Village of the Watermills Class 8 Question Answer – Activity 2

A. Look at the following sentence from
‘A Tale of Two Gifts’.
In the hall below was a letterbox too small to hold a letter.

• Can you break the highlighted word into two separate words?
What are these words?
……………………………………………………………
Answer:
Yes. The words are letter and box.

• What difference did you notice when the words are combined?
…………………………………………………………
Answer:
When combined, they form a single word (letterbox) with a specific mean- ing (a box for receiving letters), and the space between them is removed.

The word ‘letterbox’ is formed by joining the words ‘letter’ and ‘box’.
Letterbox is a compound word.

• ‘Letterbox’, ‘electric bell’ and ‘twenty-two’ are three compound words you would have noticed in the story. What differences do you notice among these compound words?
………………………………………………………………………………………………………..
Answer:
‘Letterbox’ is a closed compound word (no space). ‘Electric bell’ is an open compound word (space between words). ‘Twenty-two’ is a hyphenated compound word (hyphen between words).

B. Identify the compound words in the story and complete the table below.

Answer:

Open compound words	Closed compound words	Hyphenated compound words
electric bell	letterbox	twenty-two
gold watch	waterfall	looking-glass
Christmas Day	firewood	day-bed
linseed oil	pocketbook	ten-cent
gas plate	riverbank	beauty-shop
icebox	downstream	Hyphenated compound words
young man	watermills	twenty-two

Village of the Watermills Class 8 Questions and Answers Pdf – Lets Analysis

Activity 1

A. Read the sentences below and note the words underlined.
• He had nothing to cover his cold hands.
• He needed a new coat.

What purpose do these words serve in the sentences?
………………………………………………………………………………………………….
Answer:
These words (cold, new) describe or qualify the nouns (‘hands’, ‘coat’). They provide more information about the quality or state of the nouns.

B. Now, adorn the tree with adjectives from the story “A Tale of Two Gifts”.

Answer:

C. The following passage contains several adjectives. Some of them are highlighted but some others are missing. Read the passage and fill in the blanks with suitable adjectives, choosing from those given in brackets.
(smart, peaceful, majestic, vast, beloved)
In the park at the heart of the city, there stood an old banyan tree. Its branches stretched wide, covering a ………………. expanse. The ………………. tree stood proudly providing cool shade to everyone who visited the park. Small birds built nests on its big branches. Naja, a ………………. young girl, used to visit the park every day with her ………………. grandfather, carrying some grain to feed the birds. Thanks to her grandpa’s influence, Naja has become a true nature lover. The ………………. surroundings of the park fill her with a sense of calm and remind her of the human responsibility to preserve nature.
Answer:
In the park at the heart of the city, there stood an old banyan tree. Its branches stretched wide, covering a vast expanse. The majestic tree stood proudly providing cool shade to everyone who visited the park. Small birds built nests on its big branches. Naja, a smart young girl, used to visit the park every day with her beloved grandfather, carrying some grain to feed the birds. Thanks to her grandpa’s influence, Naja has become a true nature lover. The peaceful surroundings of the park fill her with a sense of calm and remind her of the human responsibility to preserve nature.

Activity 2

A. Read the following sentences.
1. Della’s beautiful hair fell about her, shining, like a falling stream of brown water.
2. Della knew her hair was more beautiful than any queen’s gold orgems
3. Della’s hair was the most beautiful possession she had always been proud of.

• What differences do you observe in the highlighted adjectives?
………………………………………………………………………………………………
Answer:
The highlighted adjectives show three different forms or degrees of the adjective “beautiful.” The first is the basic form (positive), the second compares Della’s hair to something else (comparative), and the third states it is superior to all others (superlative).

B. Now, complete the table below adding the comparative and superlative forms of the adjectives given. You may add more examples to the table.

Answer:

Positive	Comparative	Superlative
brave	braver	bravest
easy	easier	easiest
much/ many	more	most
beautiful	more beautiful	most beautiful
intelligent	more intelligent	most intelligent
good	better	best

C. Read the following passage about the heroes who helped the people of Kerala during the floods of 2018. Complete it, choosing the most appropriate form of the words given in brackets.

United We Stand

During the devastating floods of 2018, the people of Kerala united to carry out one of the _________ (brave/braver/bravest) rescue and relief operations in the history of the state. The Indian Armed Forces, the Kerala Police, the Kerala Fire and Rescue Services and other forces worked around the clock and their efforts proved _________ (effective/more effective/most effective). The fishermen of Kerala were among the ______ (dedicated/more dedicated/most dedicated) rescuers. Their boats were _________ (useful/ more useful/the most useful) than many other rescue vehicles, as these could move easily through the floodwaters. Urgent medical services were provided by doctors and medical teams. Volunteers of the media and technology teams helped spread awareness and ensured public safety by providing timely updates. Moreover, local volunteers and youth organizations played a _________ (significant/more significant/most significant) role in coordinating the relief efforts. The flood was one of the _________ (bad/worse/worst) disasters Kerala has ever witnessed, but the combined efforts of these brave heroes proved (strong/stronger/strongest) than the raging waters.
Answer:

United We Stand

During the devastating floods of 2018, the people of Kerala united to carry out one of the bravest rescue and relief operations in the history of the state. The Indian Armed Forces, the Kerala Police, the Kerala Fire and Rescue Services and other forces worked around the clock and their efforts proved most effective. The fishermen of Kerala were among the most dedicated rescuers. Their boats were more useful than many other rescue vehicles, as these could move easily through the floodwaters. Urgent medical services were provided by doctors and medical teams. Volunteers of the media and technology teams helped spread awareness and ensured public safety by providing timely updates. Moreover, local volunteers and youth organizations played a significant role in coordinating the relief efforts. The flood was one of the worst disasters Kerala has ever witnessed, but the combined efforts of these brave heroes proved stronger than the raging waters.

Village of the Watermills Notes – Activity 3

A. Look at the following sentence.
He looked strangely at Della.
• What is the purpose of the highlighted word?
………………………………………………………………………..
Answer:
The word ‘strangely’ describes how he looked.

• What does it modify?
………………………………………………………………………..
Answer:
It modifies the verb ‘looked’.

Here, ‘strangely’ modifies the verb ‘looked’. A word that describes or modifies a verb is an adverb.
Now, look at the highlighted words in the sentences below.
1. There was a letterbox too small to hold a letter.
2. She began to think more reasonably.

• What do these words modify?
………………………………………………………………………..
Answer:
In sentence 1, ‘too’ modifies the adjective ‘small’.
In sentence 2, ‘more’ modifies the adverb ‘reasonably’.

An adverb describes a verb and provides more information about it, or about an adjective or another adverb.

B. Examine the sentences below and underline the adverbs:
Answer:
1. The flowers were artistically arranged.
2. It was an extremely delightful function.
3. He spoke quite eloquently.
4. She selflessly gave up her dreams for the well-being of her family.
5. Her explanation was exceptionally clear.

C. Now, complete the table below, placing the adverbs in each sentence in column 1, the word each adverb modifies in column 2 and note the category of the word modified (verb/adjective/adverb) in column 3.

Answer:

Adverb	The word modified	Category of the word modified
artistically	arranged	verb
extremely	delightful	adjective
eloquently	spoke	verb
selflessly	gave up	verb (phrasal)
exceptionally	clear	adjective

D. Now collect as many adverbs as you can find in the story A Tale of Two Gifts and fill the board below:

Answer:

Activity 4

Read the following sentences:
1. I have come here to get the work done.
2. I came here yesterday to get the work done.

A. Now, try to find the differences between the sentences and note how the time and the action are expressed in each.
Sentence 1: …………………………………………………….
Sentence 2: …………………………………………………….
Answer:
Sentence 1: Describes an action completed in the past, but the time is unspecified, and the focus is on the present result (being here now). Uses Present Perfect Tense.

Sentence 2: Describes an action completed at a specific time in the past (“yesterday”). Uses Simple Past Tense.

B. Some words of time reference are given in brackets. Identify which of them match the present perfect tense and which ones match the simple past tense. Place them in the appropriate columns in the table below.
[yesterday, already, a month ago, ever, never, last week, so far, now, since, for, when I was young, recently, just, in (specific year)]

Answer:

Words usually used with verbs in the Present Perfect Tense	Words usually used with verbs in the Simple Past Tense
Words usually used with verbs in the Simple Past Tense	yesterday, last week, a month ago, when I was young, in [specific year]

C. Now, read the passage carefully. Identify the verbs/verb phrases, their tense, and the expressions relating to time. Two have been done for you.

Inspired by a thrilling music concert, Dani decided to learn the guitar. Two years ago, he bought a guitar and started attending music classes. He practised every day and soon achieved his goal of playing a number of songs. He has already mastered several chords and melodies. He has even performed with a famous music band. His dedication and hard work have brought him great success.

Answer:

Verb/Verb phrase	Tense used	Time reference
bought	simple past	last year
has mastered	present perfect	already
decided	simple past	(Implied past)
started attending	simple past	Two years ago
practised	simple past	every day (habitual past)
achieved	simple past	soon
has performed	present perfect	even
have brought	present perfect	(Implied relevance now)

Class 8 English Village of the Watermills Activities Pdf – Let’s converse:

Activity 1

Imagine a friend of yours needs help in making tea. How will you help them? The passage given below consists of instructions on how to make a cup of tea. Complete the instructions, using appropriate expressions for giving

A few expressions for instructions:
• You should…
• You may choose…
• Don’t forget to…
• It is advisable to…
• You are free to…
• Be careful…
• …………………….
• …………………….
You would first need to collect the necessary ingredients. You should take a cup of water in a pan and heat it until it boils. Then, add …………………………………………………………………………………………
…………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………………
Be careful to turn off the stove when the tea is ready. Enjoy the tea!
Answer:
You would first need to collect the necessary ingredients. You should take a cup of water in a pan and heat it until it boils. Then, add one teaspoon of tea leaves or one tea bag. You may choose to add sugar according to your taste. It is advisable to let it brew for a couple of minutes. After that, you are free to add milk if you prefer milk tea. Don’t forget to stir it well.
Be careful to turn off the stove when the tea is ready. Enjoy the tea!

Activity 2

A. The young man in ’Village of the Watermills’ reaches the village and meets the children. Feeling a little confused about the route, he asks for directions to the first watermill. If you were one of the children, how would you assist him in finding the watermill? (The first two instructions are given.)

• Turn left after the first bridge.
• Continue straight on until you come to the first watermill.
• …………………………………………………………………………………………
• …………………………………………………………………………………………
Some expressions for providing directions are given below:
• Turn right when you reach…
• Proceed to the end of…
• Walk past…
• Keep going until you find…
• …………………………………………………………………………………………
• …………………………………………………………………………………………
• …………………………………………………………………………………………
Answer:
• Turn left after the first bridge.
• Continue straight on until you come to the first watermill.
• Walk past the big tree on your right.
• You can’t miss it; you will hear the sound of the water turning the wheel.
Some expressions for providing directions are given below:
• Turn right when you reach…
• Proceed to the end of…
• Walk past…
• Keep going until you find…
• It’s on your left/right.
• Take the first/second turning on the right/left.
• Go straight across the roundabout.

B. The young man wanted to visit the old man’s house. Here is a route map to the old man’s house. Now, can you guide the young man to it?

Answer:

• Go straight ahead from where you are, past the playground.
• When you reach the river, take the boat across to the other side.
• After getting off the boat, turn right and walk along the path.
• Walk past the watermill on your left.
• Keep going straight until you see the old man’s house directly in front of you.

8th Standard English Village of the Watermills Question Answer – Let’s listen:

Shall we listen to a song now? Let’s listen to the song ‘Everything at Once’ by Lenka. Write the lyrics in your notebook. The first two lines are given below.
As sly as a fox, as strong as an ox
As fast as a hare, as brave as a bear
………………………………………………………
………………………………………………………
………………………………………………………

Village of the Watermills Questions and Answers – Let’s team up (Group Project):

We have come across many beautiful scenes in ‘Village of the Watermills Shall we try to capture a few such snapshots from nature?

Take a walk outdoors and look for beautiful scenes that catch your eye – a bird, a tree or flower, the sunset or the landscape. Click photos of the places or things you find truly attractive.

Working in groups, choose the best of these pictures and create an album – either a physical photo album or a digital album. Give each picture a meaningful caption and add a short description. Present your group album in class.

The photo albums may be added to the school library and the digital albums uploaded to the school blog or wiki.

Students often refer to Kerala Syllabus 8th Standard English Textbook Answers and Village of the Watermills in Malayalam & English before discussing the text in class.

Class 8 English Village of the Watermills Summary

Village of the Watermills Summary in English

Scene 1
EXT.* VILLAGE WITH WATERMILLS – DAY
Wide shot of a young man walking through a long wooden bridge across a river. The sound of water is heard. Watermills are at work here and there. The young man stands on the wooden bridge for a while, looking at the large gears of the watermill. Some children walk past behind him.

Children: Good day!
Young Man: Good day!
The banks are picturesque with flowers. The children cross the wooden bridge, pick some flowers and place them on a rock on the other side of the bridge. The Young Man watches this carefully.

Scene 2
EXT. VILLAGE WITH WATERMILLS – DAY
The Young Man is walking towards the wooden mills on the riverbank. There is an old man with grey hair sitting there, wearing a hat. He is adjusting the large gears of the water mill.

YOUNG MAN: Good day!
OLD MAN: (smiling) Good day!
YOUNG MAN: What’s the name of this village?
OLD MAN: It has no name. We call it ‘The Village’.
Outsiders call it ‘Village of the Watermills’.
(The Young Man smiles. Looks inside the mill.)
YOUNG MAN: Do all the villagers live around here?
OLD MAN: No, we’re spread all around.
(The Young Man looks inside the mill. He sees a lamp hanging there.)
YOUNG MAN: Don’t you have electricity here?
OLD MAN: No, we don’t need it. Nowadays, people are too used to conveniences. They think ‘the easier, the better’. They throw out what is truly good.
(The Young Man is sitting next to the Old Man who is still busy with his work.)

YOUNG MAN: But what about light?
OLD MAN: We use candles. And linseed oil.
YOUNG MAN: But the night is very dark.
OLD MAN: Yes. That’s what night is supposed to be. Why should the night shine like the day? I don’t like to see the night as bright as day. You can’t see the stars then.
YOUNG MAN: You have paddies. But, don’t you have tractors to cultivate the fields?
OLD MAN: We don’t need them. We have cows and horses.
YOUNG MAN: What do you use as fuel?
OLD MAN: Mostly firewood. We don’t feel it’s right to chop down trees … some of them fall by themselves when they are too old. We cut them up and use them as firewood. And if you make charcoal from the logs, just a few trees can give you as much heat as an entire forest. Yes … and dung is also good fuel.
Close-up of the Young Man smiling as he looks at the river. He notices the gears of the water mill turning. Long shot of trees and leaves moving in the wind. A cuckoo’s sound is heard.
OLD MAN: We try to live as true humans used to live. That is, life in the natural way. Today, people have forgotten that they are a part of nature. They destroy the nature they depend on. They think they can make life easier.
(The Young Man looks at the old man as if in disbelief.)
OLD MAN: They do not know that they are destroying nature. They don’t understand that they themselves are going to perish. The most important thing for a human being is clean air, clean water, and the trees and plants that produce them. Now everything is being polluted. Dirty water … dirty air … the very heart of man is polluted.
(Looking at the flowing stream, the Young Man stands up and looks around with curiosity.)
YOUNG MAN: On my way, I saw some children picking flowers and placing them on a stone near the bridge. What’s that?
OLD MAN: Oh that! It’s a story my father told me once. (The Young Man sits down). Once, a sick traveller died near the bridge. The villagers took pity and buried him right there. They put a big stone on his grave and put flowers on it. Later it became a custom. Not only children, all the villagers put flowers as they pass, though most don’t know why.
(The Young Man looks away in surprise.)
YOUNG MAN: (listening to a distant sound) Are there any celebrations going on today?
OLD MAN: No. It’s a funeral. You find it strange? A nice, happy funeral. It’s good to work hard and live long… and be thanked by all. We have no temples or priests. So, all the villagers take the deceased to the cemetery on the hill. It’s different if a child or young person dies. We do not like the death of young people or children. It’s hard to celebrate such a loss. Fortunately, the people of this village lead a natural way of life. So they pass on at a ripe old age. The woman who died today is 99 years old. Excuse me … I am going to join the procession.
(The Old Man gets up and prepares to go inside the house.)
To tell the truth, she was my first love. She broke my heart and left me for another.
Laughing, he goes inside a wooden house. The Young Man smiles and walks towards the river. Hearing a jingling sound, he comes back towards the house again. The Old Man comes out wearing a colourful dress and a hat, with a pair of Shinto bells in his hand.
YOUNG MAN: By the way, how old are you?
OLD MAN: Me…? One hundred and three. A good age to stop living. Some say life is hard. In fact, it’s good to be alive. It’s exciting.
He picks some flowers and walks away with a bell. The Young Man follows him.

Scene 3
EXT. VILLAGE – DAY
The procession approaches. Women, children and men move in rhythm. The little children pick flowers from the vases they hold and throw them out. Behind them are the bugle players. Then the girls. They dance beautifully. All are wearing hats. Six men carry a coffin in the middle of the procession. The children sing along. The Young Man and the Old Man stand watching the procession. The Old Man, ringing his bell holding the bunch of flowers in his hand, greets them. As the procession approaches, he joins them. All pass in front of the Young Man who curiously watches the procession, smiling. As the coffin approaches, he takes off his hat to show respect.

The music of the procession ends and then it strikes a lighter tone. The slow-moving watermills on the river are seen. The Young Man crosses the bridge, then stops and walks back to the riverbank, picks some flowers and places them on the rock. He then walks away as the river flows on.

Village of the Watermills Summary in Malayalam

Scene 1 (രംഗം 1)
EXT.* VILLAGE WITH WATERMILLS-DAY
പുറത്ത്. ജലചകങ്ങളുള്ള ഗ്രാമം – പകൽ
EXT. (Exterior): Used in screenplays to indicate that a scene takes place outdoors
(എക്സ്റ്റീരിയർ): ഒരു രംഗം പുറത്താണ് നടക്കു ന്നതെന്ന് സൂചിപ്പിക്കാൻ തിരക്കഥകളിൽ ഉപയോ ഗിക്കുന്നു.)

Wide shot of a young ……………… walk past behind him. (Text book page no.148)
നദിക്ക് കുറുകെയുള്ള നീളമുള്ള തടിപ്പാല ത്തിലൂടെ (wooden bridge) ഒരു യുവാവ് നടന്നുപോകുന്നതിന്റെ വൈഡ് ഷോട്ട് (Wide shot). വെള്ളത്തിന്റെ ശബ്ദം കേൾക്കാം. അവി ടെയും ഇവിടെയുമായി ജലചകങ്ങൾ (Watermills) പ്രവർത്തിക്കുന്നുണ്ട്. യുവാവ് അൽ പ്പനേരം തടിപ്പാലത്തിൽ നിന്ന് ജലചക്രത്തിന്റെ വലിയ ഗിയറുകളിലേക്ക് (gears) നോക്കുന്നു. കുറച്ച് കുട്ടികൾ അവന്റെ പിന്നിലൂടെ നടന്നു പോകുന്നു.
Children: Good day!
കുട്ടികൾ: ശുഭദിനം!
Young Man: Good day!
യുവാവ്: ശുഭദിനം!

The banks are ……………… watches this carefully. (Text book page no.148)
തീരങ്ങൾ (banks) പൂക്കൾ കൊണ്ട് മനോഹ – രമാണ് (picturesque). കുട്ടികൾ തടിപ്പാലം കടന്ന് കുറച്ച് പൂക്കൾ പറിച്ച് പാലത്തിന്റെ മറുവശത്തുള്ള ഒരു പാറയിൽ വെക്കുന്നു. യുവാ വ് ഇത് ശ്രദ്ധയോടെ നോക്കുന്നു.

Scene 2 (രംഗം 1)
EXT. VILLAGE WITH WATERMILLS – DAY
The Young Man is walking ……………… large gears of the water mill. (Text n book page no.149)
യുവാവ് നദീതീരത്തുള്ള (riverbank) തടി മില്ലു കൾക്ക് നേരെ നടക്കുന്നു. നരച്ച മുടിയുള്ള ഒരു വൃദ്ധ ൻ തൊപ്പി ധരിച്ച് അവിടെ ഇരിക്കുന്നുണ്ട്. അദ്ദേഹം 3. ജലചക്രത്തിന്റെ വലിയ ഗിയറുകൾ ക്രമീകരിക്കു കയാണ് (adjusting).

YOUNG MAN: Good day ……………… He sees a lamp hanging there.) (Text book page no.149)
യുവാവ്: ശുഭദിനം!
വൃദ്ധൻ: (പുഞ്ചിരിച്ചുകൊണ്ട് ശുഭദിനം!
യുവാവ്: ഈ ഗ്രാമത്തിന്റെ പേരെ ന്താണ്?
വൃദ്ധൻ: ഇതിന് പേരില്ല. ഞങ്ങൾ ഇതിനെ ‘ഗ്രാമം’ എന്ന് വിളിക്കുന്നു. പു റത്തുനിന്നുള്ളവർ (Outsiders) ഇതി നെ ‘ജലചകങ്ങളുള്ള ഗ്രാമം’ എന്ന് വിളിക്കുന്നു. (യുവാവ് പുഞ്ചിരിക്കുന്നു. മില്ലിനുള്ളിലേക്ക് നോക്കു ന്നു.) യുവാവ്: എല്ലാ ഗ്രാമീണരും (villagers) ഇവിടെ അടുത്താണോ താമസിക്കുന്നത് വൃദ്ധൻ: അല്ല, ഞങ്ങൾ പലയിടത്തായി ചിത റിക്കിടക്കുകയാണ് (spread all around).

(The Young Man looks inside busy with his work.) (Text book page no.149)
(യുവാവ് മില്ലിനുള്ളിലേക്ക് നോക്കുന്നു. അവിടെ ഒരു വിളക്ക് തൂങ്ങിക്കിടക്കുന്നത് അവൻ കാണുന്നു.) യുവാവ്: നിങ്ങൾക്ക് ഇവിടെ വൈദ്യുതി (electricity) ഇല്ലേ?

വൃദ്ധൻ: ഇല്ല. ഞങ്ങൾക്ക് അതിന്റെ ആവശ്യമില്ല. ഇന്ന ത്തെക്കാലത്ത്, ആളുകൾ സൗകര്യങ്ങളുമായി (conveniences)വളരെ ഇണങ്ങിച്ചേർന്നിരിക്കുന്നു, ‘എളുപ്പ മുള്ളതാണ് നല്ലത്’ എന്നാണ് അവർ കരുതുന്നത്. യഥാർ ത്ഥത്തിൽ നല്ലതിനെ അവർ വലിച്ചെറിയുന്നു.
(വൃദ്ധന്റെ അടുത്തായി യുവാവ് ഇരിക്കുന്നു. വൃദ്ധൻ അപ്പോഴും തന്റെ ജോലിയിൽ മുഴുകിയിരിക്കുന്നു.

YOUNG MAN: But what about light?……………. and dung is also good fuel. (Textbook page no.150)
യുവാവ്: പക്ഷേ വെളിച്ചത്തിന്റെ കാര്യമെന്താണ്?
വൃദ്ധൻ: ഞങ്ങൾ മെഴുകുതിരികൾ (candles) ഉപ യോഗിക്കുന്നു. പിന്നെ ചെറുചണ എണ്ണയും (linseed oil. യുവാവ്: പക്ഷേ രാത്രി വളരെ ഇരുണ്ടതാണ് (dark),
വൃദ്ധൻ: അതെ. രാത്രി അങ്ങനെയായിരിക്കേണ്ടതാണ്. എന്തിനാണ് രാത്രി പകൽ പോലെ തിളങ്ങുന്നത് (shine)? രാത്രി പകൽ പോലെ പ്രകാശിക്കുന്നത് എനിക്കി ഷ്ടമല്ല. അപ്പോൾ നിങ്ങൾക്ക് നക്ഷത്രങ്ങളെ (stars) കാണാൻ കഴിയില്ല.
യുവാവ്: നിങ്ങൾക്ക് നെൽപ്പാടങ്ങളുണ്ട് (paddies). പ ക്ഷേ, നിലം ഉഴാൻ (cultivate) നിങ്ങൾക്ക് ട്രാക്ടറുകൾ (tractors) ഇല്ലേ?
വൃദ്ധൻ: ഞങ്ങൾക്ക് അവ ആവശ്യമില്ല. ഞങ്ങൾക്ക് പശുക്കളും കുതിരകളുമുണ്ട്.
യുവാവ്: നിങ്ങൾ എന്താണ് ഇന്ധനമായി (fuel) ഉപ യോഗിക്കുന്നത്
വൃദ്ധൻ: കൂടുതലും വിറകാണ് (firewood), മരങ്ങൾ വെട്ടുന്നത് (chop down) ശരിയാണെന്ന് ഞങ്ങൾക്ക് തോന്നുന്നില്ല… അവയിൽ ചിലത് വളരെ പ്രായമാകു മ്പോൾ തനിയെ വീഴും. ഞങ്ങളവ മുറിച്ച് വിറകായി ഉപ യോഗിക്കുന്നു. തടികളിൽ നിന്ന് നിങ്ങൾ കരി (char- coal) ഉണ്ടാക്കുകയാണെങ്കിൽ, കുറച്ച് മരങ്ങൾ കൊണ്ടു തന്നെ ഒരു കാടുമുഴുവൻ തരുന്നത് ചൂട് ലഭിക്കും. അതെ… ചാണകവും (dung) നല്ല ഇന്ധനമാണ്.

Close-up of the Young Man …………. around with curiosity.) (Text book page no.150)
(നദിയിലേക്ക് നോക്കി പുഞ്ചിരിക്കുന്ന യുവാ വിന്റെ ക്ലോസ്-അപ്പ്, ജലചക്രത്തിന്റെ ഗിയറു കൾ തിരിയുന്നത് അവൻ ശ്രദ്ധിക്കുന്നു. കാറ്റിൽ മരങ്ങളും ഇലകളും ചലിക്കുന്നതിന്റെ ലോംഗ് ഷോട്ട്. ഒരു കുയിലിന്റെ ശബ്ദം കേൾക്കുന്നു.) വൃദ്ധൻ: യഥാർത്ഥ മനുഷ്യർ പണ്ട് ജീവിച്ചി രുന്നതുപോലെ ജീവിക്കാൻ ഞങ്ങൾ ശ്രമിക്കു ന്നു. അതായത്, പ്രകൃതിയോടിണങ്ങിയ (natural way) ജീവിതം. ഇന്ന്, തങ്ങൾ പ്രകൃതി യുടെ ഭാഗമാണെന്ന് (part of nature) ആളു കൾ മറന്നിരിക്കുന്നു. അവർ ആശ്രയിക്കുന്ന (depend on) പ്രകൃതിയെ അവർ നശിപ്പി ക്കുന്നു (destroy). ജീവിതം എളുപ്പമാക്കാമെന്ന് അവർ കരുതുന്നു.
(യുവാവ് അവിശ്വസനീയതയോടെ (disbelief) വൃദ്ധനെ നോക്കുന്നു.
വൃദ്ധൻ: തങ്ങൾ പ്രകൃതിയെ നശിപ്പിക്കുക യാണെന്ന് അവർക്കറിയില്ല. തങ്ങൾ തന്നെ ന ശിക്കാൻ (perish) പോകുകയാണെന്ന് അവർ മനസ്സിലാക്കുന്നില്ല. ഒരു മനുഷ്യന് ഏറ്റവും പ്രധാനപ്പെട്ട കാര്യം ശുദ്ധവായു, ശുദ്ധജലം, അവ ഉത്പാദിപ്പിക്കുന്ന (produce) മരങ്ങളും ചെടികളുമാണ്. ഇപ്പോൾ എല്ലാം മലിനീകരി ക്കപ്പെടുകയാണ് (polluted). മലിനജലം…
മലിനവായു… മനുഷ്യന്റെ ഹൃദയം പോലും മലിനീകരിക്കപ്പെട്ടിരിക്കുന്നു.
(ഒഴുകുന്ന അരുവിയിലേക്ക് (flowing stream) നോക്കി, യുവാവ് എഴുന്നേറ്റ് ആകാംഷയോടെ (curiosity) ചുറ്റും നോക്കുന്നു.)

YOUNG MAN: On my way, …………….. to join the procession. (Text book page no.151)
യുവാവ്: ഞാൻ വരുന്ന വഴിക്ക്, കുറച്ച് കുട്ടികൾ പൂക്കൾ പറിച്ച് പാലത്തിനടുത്തുള്ള ഒരു കല്ലിൽ വെക്കുന്നത് കണ്ടു. അതെന്താണ്?
വൃദ്ധൻ: ഓ അത്! എന്റെ അച്ഛൻ ഒരിക്കൽ എന്നോട് പറഞ്ഞ ഒരു കഥയാണ്.
(യുവാവ് ഇരിക്കുന്നു).
ഒരിക്കൽ, രോഗിയായ ഒരു യാത്രക്കാരൻ (traveller) പാലത്തിനടുത്ത് വെച്ച് മരിച്ചു. ഗ്രാമവാസികൾക്ക് ദയ (pity) തോന്നി അവനെ അവിടെത്തന്നെ അടക്കം (buried) ചെയ്തു. അവർ അവന്റെ ശവ കുടീരത്തിൽ (grave) ഒരു വലിയ കല്ല് വെച്ച് അതി ൽ പൂക്കൾ വെച്ചു. പിന്നീട് അതൊരു ആചാരമായി (custom) മാറി, കുട്ടികൾ മാത്രമല്ല, എല്ലാ ഗ്രാമീണ രും അതുവഴി പോകുമ്പോൾ പൂക്കൾ വെക്കും. എന്തിനാണെന്ന് മിക്കവർക്കും അറിയില്ലെങ്കിലും. (യുവാവ് അത്ഭുതത്തോടെ മുഖം മാറ്റുന്നു. യുവാവ് (ദൂരെ നിന്നുള്ള ശബ്ദം ശ്രദ്ധിച്ച് ഇന്ന് എന്തെ ങ്കിലും ആഘോഷങ്ങൾ (celebrations) നടക്കുന്നുണ്ടോ?

വൃദ്ധൻ: ഇല്ല. അതൊരു ശവസംസ്കാരമാണ്( funeral), നിനക്ക് വിചിത്രമായി (strange) തോന്നു ന്നുണ്ടോ? ഒരു നല്ല, സന്തോഷകരമായ ശവസംസ് കാരം, കഠിനാധ്വാനം ചെയ്ത് ദീർഘകാലം ജീവി ക്കുന്നത് നല്ലതാണ്… എല്ലാവരാലും നന്ദി പറയപ്പെ ടുന്നതും, ഞങ്ങൾക്ക് അമ്പലങ്ങളോ (temples) പുരോഹിതന്മാരോ (priests) ഇല്ല, അതിനാൽ, എല്ലാ ഗ്രാമവാസികളും മരിച്ചയാളെ (the deceased) കുന്നിൻ മുകളിലുള്ള ശ്മശാനത്തിലേക്ക് (cemetery)കൊണ്ടുപോകുന്നു. ഒരു കുട്ടിയോ ചെറു പ്പക്കാരനോ മരിച്ചാൽ അത് വ്യത്യസ്തമാണ്. ചെറുപ്പ ക്കാരുടെയോ കുട്ടികളുടെയോ മരണം ഞങ്ങൾ ക്കിഷ്ടമല്ല, അങ്ങനെയൊരു നഷ്ടം ആഘോഷിക്കാൻ പ്രയാസമാണ്.ഭാഗ്യവശാൽ (Fortunately), ഈഗ്രാമ ത്തിലെ ആളുകൾ പ്രകൃതിയോടിണങ്ങിയ ജീവിത മാണ് നയിക്കുന്നത്. അതുകൊണ്ട് അവർ നല്ല പ്രാ യമെത്തിയ ശേഷമാണ് മരിക്കുന്നത് (pass on at a ripe old age). ഇന്ന് മരിച്ച സ്ത്രീക്ക് 99 വയ സ്സായിരുന്നു. ക്ഷമിക്കണം… ഞാൻ വിലാപയാത യിൽ (procession) ചേരാൻ പോകുകയാണ്.

The Old Man gets up ……………….. Young Man follows him. (Text book page no.151)
(വൃദ്ധൻ എഴുന്നേറ്റ് വീടിനുള്ളിലേക്ക് പോകാൻ തയ്യാ റെടുക്കുന്നു.)

സത്യം പറഞ്ഞാൽ, അവൾ എന്റെ ആദ്യപ്രണയമായി രുന്നു. അവൾ എന്റെ ഹൃദയം തകർത്ത് മറ്റൊരാ ൾക്കൊപ്പം പോയി.

(ചിരിച്ചുകൊണ്ട് അദ്ദേഹം ഒരു തടിവീട്ടിനുള്ളിലേ ക്ക് പോകുന്നു. യുവാവ് പുഞ്ചിരിച്ചുകൊണ്ട് നദിക്ക് നേരെ നടക്കുന്നു. ഒരു കിലുങ്ങുന്ന ശബ്ദം (jingling sound), അവൻ വീണ്ടും വീടിനടുത്തേക്ക് വരുന്നു, വൃദ്ധൻ വർണ്ണാഭമായ വസ്ത്രവും (colourful dress) തൊപ്പിയും ധരിച്ച്, കയ്യിൽ ഒരു ജോ ഡി ഷിന്റോ മണികളുമായി (Shinto bells) പുറ ത്തേക്ക് വരുന്നു.).

യുവാവ്: വഴിയിൽ വെച്ച് ചോദിക്കട്ടെ, നിങ്ങൾക്ക് എത വയസ്സായി?
വൃദ്ധൻ: എനിക്കോ ……..? നൂറ്റിമൂന്ന്. ജീവിക്കുന്നത് നിർ ത്താൻ പറ്റിയ നല്ല പ്രായം. ചിലർ പറയും ജീവിതം ദുഷ് കരമാണെന്ന് (hard), സത്യത്തിൽ, ജീവിച്ചിരിക്കുന്നത് നല്ലതാണ്. അത് ആവേശകരമാണ് (exciting).
(അദ്ദേഹം കുറച്ച് പൂക്കൾ പറിച്ച് മണിയുമായി നടന്നു പോകുന്നു. യുവാവ് അദ്ദേഹത്തെ പിന്തുടരുന്നു.)

Scene 3
EXT. VILLAGE – DAY
The procession approaches. ……………… as the river flows on. (Textbook page no.151)
വിലാപയാത്ര (procession) അടുത്തുവരുന്നു. സ്ത്രീ കളും കുട്ടികളും പുരുഷന്മാരും താളത്തിൽ (rhythm) നീങ്ങുന്നു. ചെറിയ കുട്ടികൾ തങ്ങളുടെ കൈവശ മുള്ള പൂപ്പാത്രങ്ങളിൽ(vases)നിന്ന് പൂക്കൾ പറിച്ചെ റിയുന്നു. അവർക്ക് പിന്നിൽ കാഹളം (bugle)വായി ക്കുന്നവരുണ്ട്. പിന്നെ പെൺകുട്ടികൾ, അവർ മനോ ഹരമായി നൃത്തം ചെയ്യുന്നു എല്ലാവരും തൊപ്പി കൾ ധരിച്ചിരിക്കുന്നു. ആറ് പുരുഷന്മാർ വിലാപയാത്ര യുടെ നടുവിൽ ഒരു ശവപ്പെട്ടി (coffin) ചുമക്കുന്നു. കുട്ടികൾ കൂടെപാടുന്നു. യുവാവും വൃദ്ധനും വിലാ പയാത്ര നോക്കിനിൽക്കുന്നു. വൃദ്ധൻ, കയ്യിലുള്ള പൂച്ചെണ്ടും മണിയും കിലുക്കി അവരെ വാദ്യം (greets) ചെയ്യുന്നു. വിലാപയാത്ര അടുത്തു വരുമ്പോൾ, അദ്ദേഹം അവരോടൊപ്പം ചേരുന്നു. പുഞ്ചിരിച്ചുകൊണ്ട് കൗതുകത്തോടെ (curiously) വിലാപയാത്ര വീക്ഷിക്കുന്ന യുവാവിന്റെ മുന്നി ലൂടെ എല്ലാവരും കടന്നുപോകുന്നു. ശവപ്പെട്ടി അടു ത്തുവരുമ്പോൾ, അദ്ദേഹം ബഹുമാനം (respect) കാണിക്കാൻ തന്റെ തൊപ്പി ഊരുന്നു.

വിലാപയാത്രയുടെ സംഗീതം അവസാനിക്കുന്നു, തുട ർന്ന് അത് ലളിതമായ ഒരു ഈണത്തിലേക്ക് (lighter tone) മാറുന്നു. നദിയിലെ സാവധാനം ചലിക്കുന്ന ജല ചക്രങ്ങൾ കാണാം. യുവാവ് പാലം കടക്കുന്നു, എന്നി ട്ട് നിർത്തി നദീതീരത്തേക്ക് (riverbank) തിരിച്ചു നട ക്കുന്നു, കുറച്ച് പൂക്കൾ പറിച്ച് ആ പാറയിൽ വെക്കു ന്നു. പിന്നീട് നദി ഒഴുകുന്നതിനനുസരിച്ച് അവൻ നടന്ന കലുന്നു.

Village of the Watermills Summary by Akira Kurosawa About the Author

Akira Kurosawa (1910 – 1998) was a renowned Japanese film director, celebrated for his innovative techniques of film making and storytelling. Born in Tokyo, he directed around 30 films, including timeless classics such as Seven Samurai and Rashomon. Kurosawa’s works blend action, drama, and philosophy. He received numerous awards, including the Golden Lion at the 1951 Venice Film Festival and an Academy Award (Oscar) for Lifetime Achievement in 1990. Kurosawa’s legacy endures, influencing film-makers worldwide and leaving an indelible mark on the history of cinema.

Nadeem Noushad has translated Akira Kurosawa’s Dreams into Malayalam.