Kerala Syllabus Class 9 Chemistry Chapter 6 Notes Solutions

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Kerala SCERT Class 9 Chemistry Chapter 6 Solutions

Kerala Syllabus Std 9 Chemistry Chapter 6 Notes Solutions Questions and Answers

Class 9 Chemistry Chapter 6 Let Us Assess Answers Solutions

Question 1.
Define the following terms and answer the related questions given below.
a. Solute – What is the solute in soda water?
b. Solvent – Name the solvent that dissolves common salt.
c. Solution – Differentiate between dilute solution and concentrated solution.
d. Solubility – Explain what is meant by the solubility of copper sulphate at 25°C.
Answer:
a. The component present in a small quantity or the component that is dissolved in the solvent is called the solute.
The solute in soda water is carbon dioxide (CO₂) gas.

b. The component that is present in large quantity or that dissolves the other components in it is called the solvent.
The solvent in common salt is water.

c. A solution is a homogeneous mixture of two or more substances.
A solution containing a small amount of solute is known as a dilute solution and the one which contains a large amount of solute is known as a concentrated solution.

d. The amount of solute in grams required to saturate 100 g of a solvent at a given temperature is the solubility of the solute in that solvent.
The amount of copper sulphate present in 100 g of water at 25°C is its solubility.

Question 2.
How much water in mL is needed to dissolve 200 g potassium nitrate for preparing a solution having a concentration of 20% ?
Ans:
Mass percentage = \(\frac{\text { mass of the solute }}{\text { mass of the solution }}\) × 100
Let x be the mass of the solvent.
20 = \(\frac{200}{200+x}\) × 100
200 + \(\frac{2000}{200+x}\)
20(200 + x) = 20000
4000 + 20x = 20000
20x = 20000 – 4000
= 16000
x = \(\frac{16000}{20}\) = 800
∴ 800 mL of water is required to dissolve 200g potassium nitrate.
OR
20% = \(\frac{20}{100}\) = \(\frac{200}{1000}\)
Mass of solute = 20Qg
Mass of solution = 1000 g
∴ Mass of solvent = Mass of solution – Mass of solute = 1000 – 200 = 800 g

Question 3.
You must have seen that if sodium metal or sodium chloride salt is placed in water, it disappears. Do the two changes occur in the same way? Justify your answer.
Answer:
The changes that occur are not the same. When sodium metal is placed in water, it undergoes a chemical reaction and disappears, whereas sodium chloride does not undergo a chemical reaction; instead, it gets dissolved in water.

Question 4.
A solution of sodium chloride is given. Suggest a simple method to prove whether it is saturated or unsaturated.
Answer:
By adding more sodium chloride to the solution, we can test whether the solution is saturated or unsaturated.

• If the added sodium chloride dissolves, the solution is unsaturated.
• If the added sodium chloride does not dissolve, the solution is saturated.

Question 5.
Suppose we want to change a saturated solution to an unsaturated solution. Suggest any two methods.
Answer:
A saturated solution can be converted into an unsaturated solution either by heating or by adding more solute.

Question 6.
The solubilities of certain salts in a saturated solution prepared in 100 g water at different temperatures are tabulated below.

a. Which salt shows the maximum solubility at low temperatures?
b. How does solubility change when temperature increases?
c. What is the amount of solute required to prepare a saturated solution of potassium nitrate in 50 g water at 40°C?
d. Which salt given in the table does not show much difference in solubility with varying temperature?
Answer:
a. Sodium Chloride

b. Solubility increases with an increase in temperature.

c. From the table, the amount of solute required to prepare a saturated solution of potassium nitrate in 100 g water at 40°C = 62 g
∴ The amount of solute required to prepare a saturated solution of potassium nitrate in 50 g water at40°C = \(\frac{62}{2}\) = 31 g

d. Sodium Chloride

Question 7.
Haven’t you noticed the instruction ‘Shake well before use’ on bottles containing certain medicines?
a. To which of the following categories do these medicines belong?
(Colloid, suspension, solution)
b. What is the reason for the instruction on the label?
Answer:
a. Suspension
b. Particles of a suspension settle down over time, so shaking is required to mix them again properly.

Question 8.
Classify and tabulate the mixtures given below.
(Gold ornaments, dilute acid, muddy water, rice starch water, smoke, ink, amalgam, mayonnaise, blood, lime water, ayurvedic decoction).

True Solution	Suspension	Colloid

Answer:

True Solution	Suspension	Colloid
True Solution Gold ornaments Dilute acid Amalgam	Suspension Muddy water Lime water Ayurvedic decoction	Rice starch water Smoke Ink Mayonnaise

Question 9.
The solubility of three atmospheric gases in water is given in the graph below.

a. Which gas shows maximum solubility in water?
b. What is the solubility of oxygen at 20°C?
c. What is the change in the solubility of gases as temperature increases?
d. Suggest a method to increase the solubility of CO₂ in water.
e. Prepare a note on the solubility of gases in water compared with that of solids.
f. What may beithe changes that occur in nature if oxygen shows more solubility in water? Prepare a note.
Answer:
a. Carbon dioxide

b. 0.004g/100g

c. As temperature increases, the solubility of gases decreases.

d. Decrease temperature

e. The solubility of solids and gases in water varies based on temperature. The solubility of solids in water increases with temperature, whereas the solubility of gases in water decreases with temperature.

f. The changes that occur in nature if oxygen shows more solubility in water are:

• Atmospheric oxygen decreases. Affects living organisms.
• Amount of gases like carbon dioxide increases.
• Slow down or even prevent combustion.
• Leading to slower biological decomposition and an increase in pollutants.

Question 10.
A small crystal of copper sulphate is suspended in a supersaturated solution and ’ an unsaturated solution of copper sulphate. What will be the observation on the next day?
Answer:
When a crystal of copper sulphate is added to an unsaturated solution of copper sulphate, the crystal will dissolve, increasing the concentration of the solution.
In the supersaturated solution, copper sulphate crystal will grow larger as the excess solute in the solution begins to crystallise around it.

Question 11.
Why are stabilisers used in soft drinks?
Answer:
Stabilisers are used in order to prevent the settling of particles in soft drinks.

Extended Activities

Question 1.
Prepare a supersaturated solution of sodium silicate (Na₂SiO₃) in a trough. It dissolves easily in hot water. After it reaches room temperature, add seed crystals of various chemicals to it. Copper sulphate, ferrous sulphate, ferric chloride, cobalt chloride, nickel sulphate or other available ones can be added. Keep the trough still. After a few days, it can be seen that chemicals have grown upwards from the crystals like spikes.
Answer:
Hints:
Here are the approximate colours of the crystals you might expect to form:

• Copper Sulphate: Blue
• Ferrous Sulphate: Green
• Ferric Chloride: Yellow-brown
• Cobalt Chloride: Pink or red
• Nickel Sulphate: Green

Question 2.
You might have seen the process of making tea in the kitchen. What are the ingredients used to make tea? Present the process of making tea using a note. The presentation should include terms such as solute, solvent, solution, dissolution, insoluble, filtration, precipitation, etc.
Answer:
We need water, tea, milk, and sugar to prepare tea.

• Place a quantity of water (solvent) in a pan and heat it.
• Add a certain amount of sugar (solute) and heat it until the sugar is entirely dissolved. The resulting homogeneous mixture is referred to as a solution.
• Add tea leaves (or tea) into the solution and boil the mixture to its boiling point.
• Next, add milk and then proceed to boil once more.
• Filter the mixture through the tea strainer to collect the filtrate, which consists of the soluble substances, specifically tea, in a cup.
• The tea leaves are insoluble and are left as a precipitate in the filter.

Question 3.
You are familiar with several situations in which mixtures are used in everyday life. Make a table showing such situations and the mixtures used and present in the class.
Answer:

Situation	Mixture
Baking a cake	Flour, sugar, eggs, milk, etc.
Cleaning with a detergent	Water and detergent
Cooking a meal	Various ingredients (e.g., vegetables, spices, oil)
Drinking a soda	Water, carbon dioxide, flavourings, and sweeteners
Using toothpaste	Water, abrasives, flavourings, and fluoride
Air we breathe	Nitrogen, oxygen, carbon dioxide, and other gases
Ocean water	Water, salts, minerals, and other substances
Soil	Minerals, organic matter, water, and air

Question 4.
Diverse dietary styles and the desire to discover and try out new and delicious dishes are widespread among us. We also hear news about food poisoning nowadays. Prepare a script that calls for fostering a healthy food culture and present it in the class in the form of a play. A collage can also be made by collecting newspaper articles and other notes related to food safety.
Answer:
Hints:
Key points to include in the script:

• Food hygiene practices: Proper handwashing, cleaning surfaces and utensils.
• Safe food handling: Separating raw and cooked foods, avoiding cross-contamination.
• Proper food storage: Refrigerating perishable foods, using expiration dates.
• Beware of food allergies and intolerances.

Collage ideas:

• Newspaper articles about food poisoning outbreaks
• Food safety tips and infographics
• Images of different cuisines and food cultures
• Quotes about food and health

Solutions Class 9 Notes Questions and Answers Kerala Syllabus

Question 1.
You are familiar with many substances which are soluble in water. Can you list them?
Answer:
Common Salt, Sugar, Alcohol, Acids, Salts. Alkalies. Some of the gases.

Question 2.
Now, can you name some substances which are insoluble?
Answer:
Enamel paint, Sand, Oils, Clay, Wooden powder, Coal, Limestone

The substance that dissolves is called solute, and the substance in which the solute dissolves is called solvent. When a solute dissolves in a solvent, a solution is formed.

We have learned that sugar solution is a homogeneous mixture. Solutions are homogeneous mixtures of two or more substances.

A mixture which shows the same property throughout is a homogeneous mixture.

Another important fact is that the components in the mixture do not react chemically.

Question 3.
Some solutions are given in the table. Find out the solute and the solvent, identify their physical states.
Answer:

In most of the cases, the physical state of the solvent itself is the state of the solution.
Why is pure air a gaseous solution? Notice the diagram showing the components of atmospheric air.

We have seen that pure air is a homogeneous mixture of various gases.
How do we find out the solute and solvent in a solution?

Question 4.
Brass, which is an alloy, contains 34% zinc (Zn) and 66% copper (Cu). Find out the solute and the solvent in brass from the table and record it.
Answer:
Solute – Zinc
Solvent – Copper
The component present in lesser quantity is the solute and the component present in greater quantity is the solvent.

Question 5.
Which component in atmospheric air is the solvent? Why?
Answer:
Nitrogen. The component present in larger quantity in atmospheric air is Nitrogen.So Nitrogen is the solvent.
In aqueous solutions, water is always the solvent, irrespective of its quantity.

Question 6.
In the beginning of this lesson, we saw that there are substances which are insoluble in water and soluble in some other solvents. Which is the solvent that dissolved the enamel paint?
Answer:
Turpentine

Alcohol, carbon disulphide (CS₂), benzene (C₆H₆), carbon tetrachloride (CCl₄) etc, are some organic solvents. All liquids may not mix together to form solutions.

Question 7.
Try to dissolve kerosene, petrol etc., separately in water. Do they dissolve? What may be the reason?
Answer:
Water is a polar compound while kerosene, petrol etc are non polar compounds. A solute dissolves in a solvent based on the general principle “Like dissolves like”. That is why table salt which is an ionic compound dissolves in water, whereas others like kerosene and petrol do not. Covalent compounds generally do not dissolve in water.

How table salt dissolve in water?
Table salt (NaCl) is an ionic compound made of sodium and chlorine. Its solid-state contains organised sodium and chloride ions. Table salt crystals dissolve into an ionic solution when the attraction force between hydrated ions decreases. The Na⁺/Cl^– ions in table salt crystal dissolve in water as tiny hydrated ions. Polar solvents dissolve polar solutes. Solutes dissolve in solvents because ‘Like dissolves like’

Question 8.
Take an equal quantity of water in two beakers. Add one or two crystals of potassium permanganate (KMnO₄) to one beaker. Add five or six crystals to the second beaker.
Observe the difference in the colour of the solutions in the two beakers.
Beaker 1: Light purple colour
Beaker 2: Dark purple colour
What is the reason for the difference in the colour of the two solutions?
Answer:
It is due to the difference in the amount of solute dissolved in the solution.
The solution containing a greater amount of solute is said to be more concentrated.
From this, we can understand that the concentration of a solution depends on the amount of solute.

The concentration of a solution refers to the amount of solute dissolved in a fixed amount of solvent. A solution containing a small amount of solute is known as a dilute solution and the one which contains a large amount of solute is known as a concentrated solution.

There are several units to express the concentration of a solution.

Question 9.
For example, if 10 g common salt is dissolved in 90 g water how is the concentration calculated
in terms of mass percentage?
Answer:
Mass of solute = 10 g
Mass of solvent = 90 g
Mass of solution = 10 g + 90 g = 100 g
Mass percentage of solution = \(\frac{10}{100}\) × 100 = 10%
What does it mean if the concentration of the common salt is 15 %?
It can be understood that 15 g of common salt is present in 100 g of the solution.

Question 10.
A solution is prepared by dissolving 2 g of substance A in 18 g water. Calculate the mass percentage of the solution.
Answer:
Mass of solute = 2 g
Mass of solvent = 18 g
Mass of solution = 2g + 18g = 20g
Mass percentage of solution = \(\frac{2}{20}\) × 100 = 10%
The concentration of solvents in terms of mass percentage is important in the production of many products in the industry.
For example, the bleaching solution used for industrial purposes is the aqueous solution of 3.62 mass percentage of sodium hypochlorite. This shows the importance of accuracy in measurement.

Question 11.
You saw that when a saturated solution of ammonium chloride was prepared, a little solute remained undissolved. Is it possible to dissolve it?
Try heating it. Add some more ammonium chloride and continue heating. What happens? Does the solute dissolve?
Answer:
Heating a saturated solution of ammonium chloride increases its solubility, allowing more solute to dissolve. However, if you keep adding solute to the heated solution, it will eventually become saturated again and no more solute will dissolve.

Question 12.
Now, leave the solution undisturbed and allow it to cool gradually to room temperature. Does the solute get precipitated? Record your observations.
Answer:
Yes, the solute will get precipitated when the solution cools down to room temperature. As the temperature decreases, the solubility of ammonium chloride in water also decreases. This means that the solution can no longer hold as much dissolved ammonium chloride as it could at a higher temperature. As a result, the excess ammonium chloride will precipitate out of the solution, forming crystals.

A solution which contains more amount of solute than required to saturate it at a particular temperature is called supersaturated solution.

Question 13.
Prepare supersaturated solutions of copper sulphate (CuSO₄) and potassium nitrate (KNO₃) in separate beakers. Into these solutions, hang one small crystal each (seed crystal) of copper sulphate and potassium nitrate using a thread. What change do you observe after some time? Observe it again after a day. Record your observations.
Answer:
We can see that the crystals are growing. This is due to more amount of solutes attaching to the crystals. This process will continue until the solution becomes saturated.

The process by which crystals of the solute are formed when a supersaturated solution is cooled slowly is called crystallization.

Question 14.
Take 50 mL water each in two beakers. Take 100 g each of powdered common salt (NaCl) and sodium bicarbonate (NaHCO₃) in separate dishes. Prepare saturated solutions by adding common salt to the first beaker and sodium bicarbonate to the second beaker in small portions, stirring slowly. By calculating the amounts of the two salts remaining in each dish from 100 g solute, we can find out the amount of solute required to prepare the saturated solution. Did the two solutes dissolve to the same extent?
Record your observations.
Answer:
You will likely find that sodium chloride is more soluble in water than sodium bicarbonate. This means that more sodium chloride can dissolve in a given amount of water compared to sodium bicarbonate. Therefore, the saturated solution of sodium chloride will contain a higher concentration of dissolved salt than the saturated solution of sodium bicarbonate.

The amount of solute in grams required to saturate 100 g of a solvent at a given temperature is the solubility of the solute in that solvent.

Here, we can see that it is the nature of the substance that affects solubility. You have learnt from the previous experiments that a change in temperature affects solubility.

Question 15.
Does solubility increase with an increase of temperature?

Let us examine the graph given below. This is called a solubility curve.
This is a graph that shows the solubility of certain salts in with respect to temperature.

a. What is the change that generally occurs in solubility with a rise in temperature? Increases/Decreases
Answer:
Increases

b. Which is the substance whose solubility decreases with a rise in temperature?
Answer:
Calcium Sulphate

c. Which substance shows maximum solubility at 30°C?
Answer:
Potassium Nitrate

d. What is the peculiarity in the solubility of sodium chloride compared to other salts?
Answer:
Its solubility is the same in almost all temperatures.

e. Prepare a note on the relation between temperature and solubility.
Answer:
The solubility of almost all substances increases with rise in temperature.
Example: Potassium Chloride and Potassium Chlorate
The solubility of a few substances, like calcium sulphate, decreases with a rise in temperature. The temperature has no influence on the solubility of certain substances like sodium chloride.

Are there any other factors which influence solubility?
We can see that sodium chloride is highly soluble in water. But it is only slightly soluble in alcohol, and insoluble in kerosene. This may be due to the difference in the nature of the solvents. Normally carbon dioxide (CO₂) gas is only slightly soluble in water. You must have seen that when a bottle of soda is opened, CO₂ gas comes out from the bottle with a brisk effervescence. Soda water is prepared by dissolving carbon dioxide in water under high pressure. When the bottle is opened, the pressure decreases, causing the carbon dioxide to come out as bubbles.

Question 16.
Which is the factor that affects solubility here?
Answer:
Pressure

Question 17.
On the basis of the observations you have made so far, try to list the factors which affect solubility. Answer:
1. Nature of the solute ‘
2. Temperature
3. Pressure
4. Nature of the solvent

Question 18.
Note the given solubility curve of Glauber’s salt (Na₂SO₄.10H₂O).

Find out the characteristics of the solubility of Glauber’s salt that differentiate it from other salts.
Answer:
The solubility of Glauber’s salt at 0°C is 47.6 g. On heating, the solubility increases to a certain point and reaches the maximum solubility of 49.7 g at 32.4°C. It can be seen that its solubility decreases on further heating above 32.4°C. Above 32.4°C, the kinetic energy of the solute molecules increases and the molecular structure Na2S04 is attained. Due to this, heat is liberated and the solubility tends to decrease. Glauber’s salt is cited as an example of anomalous solubility.

Question 19.
Are solutions formed when substances are mixed together? Let us mix it up.
Beaker 1: Water + sugar
Beaker 2: Water + chalk powder

a. Stir the contents in both beakers well, and observe.
In which of these beakers are the particles visible?
Answer:
Beaker 2

b. Let us examine the beakers after keeping them undisturbed for some time.
In which of these beakers did the particles settle down?
Ans:
Beaker 2

c. Stir the mixtures in both the beakers well, and pass an intense beam of light through the sides of the beakers.
In which of these beakers is the path of the light beam visible?

Answer:
Beaker 2

d. Filter each mixture using filter papers. Particles of which beaker could be separated?
Answer:
Beaker 2

The mixture of sugar and water is a true solution. Since it is a homogeneous mixture, it has a uniform composition throughout the mixture. The mixture of chalk powder and water is known as a suspension.

If the components in a mixture are not distributed uniformly, it is known as a heterogeneous mixture.

Question 20.
Find out more examples of heterogeneous mixtures.
Answer:
Mixture of water and chalk powder
Muddy Water
Paint
Mixture of oil and water
Ayurvedic decoction

Question 21.
Based on which aspects do we consider muddy water as a suspension?
Answer:
Muddy water is considered a suspension because:

• The particles are visible.
• The particles can be separated.
• The particles do not dissolve.

Question 22.
Now, you can tabulate the characteristics of a true solution and a suspension, from what you have observed. Fill up the blank spaces.
Answer:

Activity	True solution	Suspension
Filtering using a filter paper	Particles cannot be separated by filtration.	Particles can be separated by filtration.
Passing an intense beam of light	Path of light beam is not visible	Path of light beam is visible.
Keeping it undisturbed	Particles settle down	Particles do not settle down

The reason for the difference in observations is due to the difference in the size of the solute particles. The size, of the solute particles is very small in a true solution. They cannot be seen with naked eye Qr even a microscope. As the particles are very minute, they cannot scatter a beam of light. Hence, the path of light beam is not visible. In the case of a suspension, the solute particles are large enough to be seen with the naked eye. They scatter light. They gradually settle down due to gravity. We can filter these out also.

Question 23.
Take a mixture of water and milk in a beaker and repeat the previously done activity. Tick (√) your observations.
Answer:

We cannot see the particles in it with the naked eye as in a solution. They also do not settle down as in a suspension. But on passing an intense beam of light, the path of the beam is visible.

Colloidal mixtures are intermediate between solutions and suspensions. Hence, we can understand that milk is a colloid.

Question 24.
In cinema theatres and smart classrooms where visuals are shown using a projector, have you noticed that the path of light beam can be clearly seen if there are dust particles in air? What is the reason for this?
Answer:
The size of the dust particles is equal to the particle size of colloids. The reason why the path of the
light beam is visible in a dusty room is because the dust particles scatter the light in all directions. This scattered light enters our eyes, making the path of the beam appear visible.

Question 25.
By analysing the above activities, list the characteristics of true solution, suspension and colloid.
Answer:

True solutions	Suspensions	Colloids
• When kept undisturbed, particles do not settle down • Particles cannot be separated by filtration • On passing an intense beam of light, the path of the light beam is not visible. • Particle size (in nm) is 0.1 to 1 nm	• When kept undisturbed, particles settle down • Particles can be separated by filtration • On passing an intense beam of light, the path of the light beam is visible. • Particle size (in nm) is more than 1000 nm	• When kept undisturbed, particles do not settle down • Particles cannot be separated by filtration • On passing an intense beam of light, its path is visible • Particle size (in nm) is 1 to 1000 nm

Let us do an experiment.

Question 26.
Prepare a solution by adding 2g sodium thiosulphate (Na₂S₃O₃.5H₂O) to a beaker containing 50 mL of water. Place the beaker in the path of a beam of light, add a few drops of dilute hydrochloric acid, and stir well. Observe for a while. Record your observation.
Answer:
As a result of the chemical reaction, sulphur gets precipitated in colloidal form. A path of the light beam is formed. With the passage of time, more and more sulphur particles get separated, and the size of the particles increases. Finally, sulphur settles down in the form of suspension.

The phenomenon of scattering of a beam of light by colloidal particles is known as Tyndall effect.

Question 27.
Try to find out more examples of this phenomenon from daily life.
Answer:

• Sunlight filtering through trees: The dust particles in the air scatter the sunlight, making the beams visible.
• Foggy mornings: The water droplets in the fog scatter sunlight, creating a hazy appearance.
• Sunbeams through clouds: The light scatters off tiny water droplets in the clouds, creating a visible path.
• Car headlights in fog: The light scatters off the fog particles, making the beam visible.
• Smoke from a campfire: The smoke particles scatter sunlight, making the smoke appear visible.

Question 28.
Colloids have several applications in the modern world. Food production, treatment of wastewater, production of cosmetics, medicines, oil/water emulsions, mayonnaise, gels, and dairy products are all related to colloids. Identify the ingredients used in these and prepare a note. Present it in the class.
Answer:
Colloidal mixtures are intermediate between solutions and suspensions. We cannot see the particles in it with the naked eye as in a solution. They also do not settle down as in a suspension. But on passing an intense beam of light, the path of the beam is visible. Colloids play a vital role in various industries and in everyday life.

Food Production

• Milk: A colloid of fat droplets dispersed in water.
• Mayonnaise: An emulsion of oil in water, stabilised by egg yolk.
• Ice cream: A colloid of air bubbles dispersed in a mixture of milk, cream, sugar, and flavourings.
• Whipped cream: A colloid of air bubbles dispersed in cream.

Cosmetics

• Lotions and creams: Emulsions of oil in water or water in oil.
• Sunscreens: Colloids of zinc oxide or titanium dioxide dispersed in a liquid.
• Mascara: A suspension of pigments in a liquid.

Medicines

• Drug delivery systems: Colloids can be used to deliver drugs to specific tissues or organs.
• Vaccines: Often contain colloids of antigens or pathogens.
• Nanoparticles: Used in drug delivery and imaging.

Gels

• Hair gel: A gel of polymers in water.
• Contact lens solution: A gel of polymers in water.

All colloids are made up of two important components. They are dispersion medium and dispersed phase. Dispersed phase will be dispersed in dispersion medium Thau are eight major sub classes of colloids. They differ according to the physical state of the above two components.

Question 29.
How long are they fit for consumption?
Answer:
These natural drinks are best consumed fresh to retain their taste, nutrients, and health benefits. Chemical substances can be added to preserve them for a long time. The chemicals added to beverages in order to prevent the settling of particles are called stabilisers.

Some Stabilisers are

• Brominated vegetable oil
• Sucrose acetate isobutyrate
• Glyceryl ester of rosin

Substances used to prevent the spoilage of food are commonly known as preservatives. Examples are vinegar and salt.
Preservatives maintain the quality or enhance the taste of food. Certain chemicals are added to artificial drinks to give them attractive colours.
Some of such chemicals are given in the table.

Soft drinks are also known as carbonated drinks, fizzy drinks and pop drinks. Many of these are made by passing carbon dioxide through water, adding artificial colours, preservatives, sucrose or artificial sugar, caffeine etc. Artificial sweeteners can stimulate our taste buds and make us crave more sweets. Aspartame, saccharin, fructose com syrup, etc., which are many times sweeter than sugar and relatively cheaper, are the main villains in sweets.

Question 30.
Do soft drinks have any nutritive value?
Answer:
Soft drinks may provide temporary refreshment, but they offer virtually no nutritional benefits and can have negative health effects when consumed frequently.

Question 31.
How do such chemical substances which are added to food and drinks affect the body?
Answer:
Although these soft drinks have fewer calories than sugar, they raise blood triglycerides, produce unhealthy fats, and cause other health issues. Soft drinks can cause non-alcoholic liver cirrhosis and excess hunger. Such sweeteners raise uric acid in the blood and cause various disorders. Soft drink use can also induce obesity and tooth problems, according to studies.