Kerala Syllabus Class 8 Basic Science Model Question Paper Set 3

To reduce exam fear, Class 8 Basic Science Question Paper Kerala Syllabus Set 3 provide good practice.

Kerala Syllabus 8th Standard Basic Science Model Question Paper Set 3

Time: 2 hour
Total score:60

Instructions:

1. The first 15 minutes is cool-off time. This time is meant for reading the questions and planning your answers.
2. This question paper includes 10 questions in sections A, B and C
3. You need to answer only one of the options provided for each of the choice-based questions.

PHYSICS

Time: 40 minutes
Total Score: 20

Section – A

Select the correct answer for questions 1 to 2. Answer all questions. (1 score for each question) (2 × 1 = 2)

Question 1.
The pressure exerted on an area of 10 m₂ by a force of 5 0 N is _____
a) 5 N
b) 5 N/m₂
c) 0.2 N/m₂
d) 0.2 N
Answer:
b) 5 N/m₂
P = \(\frac{\mathrm{F}}{\mathrm{~A}}\), F = 50 N, A = 10₂
P = \(\frac{\mathrm{50}}{\mathrm{10}}\) = 5 N/m₂

Question 2.
Two statements related to image formation in a spherical mirror is given. Examine them and choose the correct answer.
Statement l:When an object is placed at C of concave mirror, size of image formed is as that of object.
Statement 2 :When the object is placed at F of a concave mirror ,we can imagine that the image is formed at infinity.
a) Both statements are correct
b) Only the second statement is correct
c) Only the first statement is correct
d) Both statements are incorrect
Answer:
a) Both statements are correct

Section – B

Answer questions 3 to 8 in more than one sentence. Questions 4 and 6 have choices. (2 score for each question) (6 × 2 = 12)

Question 3.
“Overspeed of vehicles result in accidents”
Write two messages to be written on an awareness board in your school premises to minimise road accidents.
Answer:

1. Speed thrills but kills
2. Don’t mix drink with drive.
3. Wear helmets while driving motor cycles. (Any two)

Question 4.
A. Write down the following units in descending order of their values.
a) 2 cm, 2 m, 2 km, 2 mm
b) 5g, 5 mg, 5 quintal, 5 kg
Answer:
a) 2 km > 2 m> 2 cm > 2 mm
b) 5 quintal > 5 kg > 5 g > 5 mg

OR
B. Complete the table.

Unit	Symbol
Newton	(a)….
Kelvin	(b)….
Ampere	(c)….
Metre	(d)….
Kilogram	(e)….
Second	(f)….

Answer:

Unit	Symbol
Newton	(a) N
Kelvin	(b) K
Ampere	(c) A
Metre	(d) M
Kilogram	(e) K
Second	(f) S

Question 5.
Liquids also exert pressure. Write down any two factors that influence liquid pressure.
Answer:
i) Height of the liquid column
ii) Density of the liquid

Question 6.
A. Find out the magnetic polarity indicated by A and B in the figures given below.

Answer:
Fig(a) A-North pole
Fig(b) B-South pole

B. Some of the devices are mentioned below.
Electric bell, Maglev train, Compass needle, Generators, Magnetic toys
a) From the given devices classify them as electromagnets and permanent magnets?
b) What are the differences between Electromagnets and permanent magnets?
Answer:
a) Electromagnets: Electric bell, Maglev trains, Generators
Permanent magnets: Compass Needle, Magnetic toys

b)

Electromagnets	Permanent magnets
• Poles can be changed.	• Poles are fixed
• Strength can be increased by changing current or number of turns of coil.	• Magnetic strength cannot be increased.
• Magnetism exists only when current flows	• The gained magnetism can be retained for a long time.

Question 7.
A negatively charged rod is brought near an electroscope as shown in the figure.

Copy down the diagram and mark the distribution of electric charge formed at A and B
Answer:

Question 8.
Fill in the blanks.
a) In a spherical mirror, the distance from the pole to the pnncipal focus is called the ______
b) The focal length of a mirror having radius of curvature 18 cm is ______
Answer:
a) Focal length
b) 9 cm

Section – C

Questions 9 to 10 carry 3 score each . Question 10 has a choice. (2 × 3 = 6)

Question 9.
a) Earth is considered as an electron bank why?
b) Observe the figure.

If the plate B is earthed, what change occurs. Draw the picture.
Answer:
a) When a positively charged body is earthed, electrons flows from earth to body. When a negatively charged body is earthed. electrons flows from body to earth. Thus earth receives and gives electrons, so earth is called an electron bank.
b)

Question 10.
A. a) Complete the diagram given below by drawing normal and the path of the reflected rays.

b) Complete the diagram given below by drawing the path of the reflected rays.

c) The principal focus of a concave mirror is real? Why?
Answer:

c) In a concave mirror, the rays that fall parallel to the principal axis converge to the principal focus and it can be caught on a screen. Hence, its principal fochs is real.

OR
Question 10.
B. Classify the following statements as to those related to uses of concave mirrors and convex mirrors and tabulate them accordingly.
a) as make up mirror
b) as rear view mirrors in vehicles
c) in solar concentrators
d) as shaving mirror
e) Dentist mirror
f) Reflectors in street lamps
Answer:
Concave mirrors Convex mirrors
a) as make up mirror
b) as rear view mirrors in vehicles
c) in solar concentrators
f) Reflectors in street lamps
d) as shaving mirror
e) Dentist mirror

CHEMISTRY

Time: 40 minutes
Total Score: 20

Section – A

Answer all the questions from 1 to 2. 1 score each.

Question 1.
Match the following.

Common Name	Chemical formula
i) Caustic soda	a) KOH
ii) Milk of lime	b) NaOH
iii) Caustic potash	c) Ca(OH)2

Choose the correct order.
A) i-b. ii-a, iii-c
B) i-c, ii-b. iii-a
C) i-c. ii-a, iii-b
D) i-b, ii-c, iii-a
Answer:
D) i-b, ii-c, iii-a

Question 2.
Two statements are given.
Statement 1: Soda-lime glass, Borosilicate glass. Flint Glass contain silica.. Statement 2: Silica is the component present in all types of glass.
Select the correct option from the following.
A) Both statements 1 and 2 are correct.
B) Statement 1 is correct. But statement 2 is not correct.
C) Statement 2 is correct. But statement 1 is not correct.
D) Both statements 1 and 2 are not correct.
Answer:
Select the correct option from the following.

Section – B

Two questions from 3 to 8 have choices. Each question carries 2 scores. (6 × 2 = 12)

Question 3.
The observation result of an experiment is given below. Identify the gases formed

Acids	Substance	Gas
Vinegar	Zinc piece	___(a)___
Vinegar	Baking soda	___(b)___

Answer:
a) Hydrogen gas (H₂)
b) Carbon Dioxide (CO₂)

Question 4.
A) Write any two merits and demerits of synthetic fibres.
Answer:
Merits: Less expensive, High durability. Wrinkle-free.
Demerits: Do not absorb water, Less air circulation.

OR
B) Synthetic fibres are generally used by blending them with natural fibres. Why?
Answer:
To give extra strength.
• To give a new texture.
• To bring extra qualities

Question 5.
Water expands when it freezes.
a) What change happens to its volume and density?
b) How does this property help aquatic life in cold regions?
Answer:
When water freezes, its volume increases and
its density decreases. This is why ice is lighter than water and floats on its surface.

b) Ice floats on water because its volume increases (density decreases) when it freezes. Floating ice acts as a protective layer (insulator). This insulation prevents the water below from freezing. This allows fish and aquatic life to survive in cold regions.

Question 6.
Take a small piece of zinc in a test tube. Add a little dilute hydrochloric acid to it. Hold a burning matchstick at the mouth of the test tube.
a) What do you observe?
b) Name the gas formed here?
Answer:
a) When you hold a burning matchstick or splinter near the mouth of the test tube, the gas will ignite and bum with a “pop” sound.

b) Hydrogen gas. (When acids react with highly reactive metals, hydrogen gas is produced.)

Question 7.
a) What are the components of water?
b) How can we separate the components of water?
Answer:
a) Hydrogen, Oxygen
b) Water can be split into its components by passing electricity through it.

Question 8.
A) Which properties of metals are used in the following situations?
a) Copper is used to make bells.
b) Tungsten is used to make the filament of a light bulb.
Answer:
a) Sonority – the ability to produce a specific sound when struck with a hard object.
b) Ductility – the ability to be formed into a very thin sheet.

OR
B) Which properties of metals are utilised in the following cases?
a) Iron is used to make weapons.
b) Aluminium is used to make food packaging.
Answer:
a) Hardness
b) Malleability

Section – C

One question from 9 to 10 have choice. Each question carries 3 scores. (2 × 3 = 6)

Question 9.
Write what type of chemical reaction each of the following is:
a) Fireflies emit light.
b) When zinc and copper nails are inserted into a lemon and connected to an LED through a copper wire, the LED glows.
c) Ammonium chloride decomposes when heated strongly.
Answer:
a) Bioluminescence.
b) Electrochemical Reaction.
c) Thermochemical reactions.

Question 10.
A) A few polymers and their characteristics are given in the table. Complete the table based on their
characteristics.
[Rubber, Fibre, Plastics, PVC (Polyvinyl chloride)]

Characteristics	Polymer
Suitable for making strong threads.	____(a)____
A polymer that can be moulded into various shapes.	Plastic
Polymer with elastic nature.	____(b)____
Polymer with electrical resistance.	____(c)____

Answer:
a) Fibres
b) Rubber
c) PVC (Polyvinyl chloride)

OR
B) Consider the apparatus as shown in the figure. Heat the water in the flask.

a) When does the temperature remain constant?
b) What happens to the water when the temperature remains constant?
c) Why does the temperature not rise even when heat is supplied?
Answer:
a) At 100°C
b) Water starts boiling.
c) The temperature does not rise above 100°C because the heat supplied is being used to overcome the intermolecular forces of attraction between the water molecules and change the water’s state from liquid to gas.

BIOLOGY

Time: 40 minutes
Total Score: 20

Section – A

Choices are given for questions 7, 8, 10. Answer questions 1 and 2. Each question carries 1 score. (2× 1 = 2)

Question 1.
Scientists who advanced the theory of chemical evolution
a) Harold Urey, Stanley Miller
b) Oparin, Haldane
c) Sidney Fox, Joan Oro
d) Watson. Crick
Answer:
b) Oparin, Haldane

Question 2.
Examine the statement and the reason, and choose the correct answer.
Statement (S): Carl Linnaeus is known as the Father of Taxonomy.
Reason (R): Linnaeus introduced the different levels of classification and provided a scientific basis for classification. He also introduced the scientific method of naming organisms called Binomial Nomenclature.
a) Both S and R are true, and R is the correct explanation of S.
b) Both S and R are true, but R is not the correct explanation of S.
c) A is true, but S is false
d) A is false, but S is time
Answer:
a) Both S and R are true, and R is the correct explanation of S.

Section – B

Write answers to questions 3 to 8. Each question carries 2 score.

Question 3.
Over time, complex organisms evolved into the plants and animals we see today.
a) When is life thought to have originated on Earth?
b) What conditions led to the formation of complex organisms?
Answer:
a) Scientists believe that life originated on Earth about 3.5 billion years ago.
b) Some of the simpler organisms released oxygen through photosynthesis, which led to the formation of more complex organisms.

Question 4.
Observe the given figure and answer the following questions:

a) Identify A and B in the given figure.
b) Write about the shape and motility of A and B.
Answer:
a) A – Male gamete (Sperm)
B – Female gamete (Ovum/Egg)

b) Shape of A- Tadpole like shape, Shape of B – Spherical in shape.
Motility of A- Tail helps in the motility, B- It is not motile.

Question 5.
Choose and write the correct pairs.
(A) Matthias Jacob Schleiden discovered that all plants are made of cells
(B) Theodor Schwann – introduced the idea that new cells arise from existing cells
(C) Rudolf Virchow discovered that all animals are made of cells
(D) Ernst Ruska and Max Knoll invented the electron microscope.
Answer:
A and D

Question 6.
A) Complete the table given below:

Ecological Interaction	Examples
Predation	a _____
b _____	Mango tree and vanda
c _____	Mango tree and loranthus

Answer:
A) Deer and Tiger.
b) Commensalism,
c) Parasitism

B) What is trophic level? Which organism belongs to the first trophic level in the food chain
Answer:
Trophic level is the position of an organism in the food chain. l?lants belong to the first trophic level.

Question 7.
A. Differentiate between drip irrigation and wick irrigation.
Answer:
Drip irrigation – This is an irrigation method that uses pipes and valves to deliver water in droplets to the root zone. This minimises water loss and ensures that all plants receive the same amount of water. Wick irrigation This method delivers water directly from the water source to the root zone of plants using a cotton wick. It requires less water than drip irrigation.

OR
B. ‘Farming will be profitable only if all the pests are killed!’
What is your response to this comment from a farmer? How can effective pest control be implemented?
Answer:
I do not agree with this opinion of the farmer. Pest control methods should be selected taking into account the density and nature of the crops. The farmers’ need is not to kill the entire pests, but to control their growth in a way that does not damage the crops. Integrated pest control is a method that minimises the use of pesticides through automated pest control methods using various types of nets and traps, friendly insects, and the cultivation of seeds that are resistant to pests.

Question 8.
A. If there is a mistake in the statements given below, correct the mistake by changing only the underlined word.
a) The cell wall is the hard outer layer of the cell membrane.
b) The cell membrane provides protection and shape to the cell.
c) The cell wall in plants is mainly made of cellulose.
d) Substances enter and leave the cell through the Golgi apparatus.
Answer:
b) The cell wall provides protection and shape to the cell.
d) Substances enter and leave the cell through the cell membrane.

OR
B. Observe the picture and answer the questions below.

a) Which is the complex tissue represented by the picture?
b) What is the function of this complex tissue?
Answer:
a) Xylem
b) The conduction of water and salt to the leaves takes place through the xylem.

Section – C

Answer questions 9 and 10. Each question carries 3 score. (2 × 3 = 6)

Question 9.
Answer the following questions related to twins:
a) Give one characteristic that is always true for Identical twins regarding their sex.
b) Why is the external appearance of Fraternal twins usually different?
c) State the two major consequences (results) of the incomplete division or fusion that defines Conjoined twins.
Answer:
a) They will always belong to the same sex.

b) Fraternal twins develop from two different eggs fertilized by two different sperms. Therefore, they have different genetic material, which results in different external appearances and hereditary traits.

c) Body parts will be joined together, the external appearance and hereditary traits of the offspring will be the same.

Question 10.
A. Observe the illustration and answer the questions below.

a) Who performed the experiment shown in the illustration?
b) What is the source of energy in this experiment?
c) How does this experiment validate the theory of chemical evolution?
Answer:
a) Harold Urey and Stanley Miller
b) Electric spark
c) This experiment was conducted by artificially recreating the conditions of the primitive Earth in the laboratory. This experiment was able to produce amino acids, which are organic molecules. This experiment proved that organic molecules can be formed from inorganic components under suitable conditions.

Question 10.
B. Arrange the timeline properly.

Answer: