JKSCERT Class 8th Science Model Paper Solved

"Check JKSCERT Class 8th Solved Model Paper 2023-24. The Solutions have been prepared in simple and concise language to suit my children at Govt Schools"

JKSCERT Class 8th Solved Model Paper 2023-24; Mufawad

Section A

Multiple Choice Questions (13×1=13)

Choose the Correct option:

Q1. If „O‟ is microorganism which lives in water and reproduces by budding. Identify the organism O from the microorganisms given below:

(A) Euglena (B) Paramecium (C) Coral (D) Planarians

Ans: C. Corals

Corals reproduce by Budding or Fragmentation. They are Marine Invertebrate animals and belong to Cnidarias which also include Jelly Fish.

Other organisms named above reproduce by Binary Fission or Multiple Fission.

Q2. The number of images formed by two adjacent plane mirrors depends on the angle between the mirrors as shown in figures below. Find the number of images formed when angle between mirrors is 60°.

(A) 6 (B) 5 (C) 3 (D) 4

Ans: 5 Images

The Formula to know number of images formed between two mirrors is given by θ/360 -1.

Q3. Identify the natural source of air pollution.

(A) Automobile exhausts (B) Smoke from factories

Ans: (D) Volcanic eruptions and forest fire

Q4. The chemical formula of the rust.

(A) Fe3O4 (B) FeO (C) Fe2O3 (D) Fe(OH)₂

Ans: Fe2O3

FeO is called Ferrous oxide, Fe2O3 is called Ferric oxide, which is also called Rust. Fe3O4 can also be written as FeO.Fe2O3 and is also called Magnetic Iron Oxide.

Q5. Water which is suitable for drinking is called.

Sewage water (B) Fresh water (C) Potable water (D) Sea water

Ans: (C) Potable water

Q6. The way that is not used to conserve water?

Reuse (B) Reduce (C) Recycle (D) Replace

Ans: (D) Replace

Q7. Identify the microorganisms shown in the figure below:

(A) A-Giardia, B-Trypanosoma, C-Euglena, D-Amoeba

(B) A- Amoeba, B-Trypanosoma, C-Paramecium, D- Giardia

D-Amoeba (D) A- Euglena, B- Giardia, C- Amoeba, D- Trypanosoma

Ans: (A) A-Giardia, B-Trypanosoma, C-Euglena, D-Amoeba

Case Based Questions (Q8-Q10) Case:

A student performed an activity to show the effect of manure and fertilizers on the growth of seedlings. He took three pots A, B and C with same kind of seedlings as shown below. Pot A contains ordinary soil without any manure or fertilizer, Pot B contains soil that is mixed with manure and Pot C contains soil mixed with fertilizer.

The important types of manures are Farmyard Manure (FYM), Green Manure (GM), Compost, Sea Manure and Poultry Manure. While, the important types of fertilizers are Nitrogen, Phosphate, and Potash (NPK). Other fertilizers are Urea, Calcium Ammonium Nitrate (CAN) etc.

Q8. Which Pot contains soil that is mixed with Potash or Urea?

(A) Pot A (B) Pot B (C) Pot C (D) In Pot B and Pot C

Ans: (C) Pot C

Potash and Urea are Fertilizers, Hence Pot C

Q9. Pot C shows the maximum growth in comparison to Pot B, this is because:

(A) Fertilizers are not good for plants

(B) Fertilizers are not soluble in water

(D) Fertilizers have all the nutrient that a plant needs.

Ans: (D) Fertilizers have all the nutrient that a plant needs.

Q10. Identify correct match of Manure and Fertilizer.

(A) GM is Chemical Fertilizer and FYM is Chemical Fertilizer

(B) CAN is Chemical Fertilizer and NPK is Manure

(D) NPK is Chemical Fertilizer and FYM, GM is Manure.

Ans: (D) Fertilizers have all the nutrient that a plant needs.

Assertion and Reasoning Type Questions

(Q11-Q13) Directions: In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R).

Mark the correct choice as:

(A) Both Assertion (A) and Reason (R) are true and reason (R) is the correct explanation of assertion (A).

(B) Both Assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

(D) Assertion (A) is false but Reason (R) is true.

Q11. Assertion (A): The bubbles of a gas may be formed on the electrodes.

Reason(R): The passage of an electric current through a conducting solution causes chemical reaction.

Ans: (A) Both Assertion (A) and Reason (R) are true and reason (R) is the correct explanation of assertion (A).

Q12. Assertion (A): Graphite is a non-metal.

Reason(R): It is the only non-metal which is good conductor of electricity.

Ans: (B) Both Assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Q13. Assertion (A): Lighting strikes could destroy life and property.

Reason(R): Lighting conductors can protect buildings.

Ans: (B) Both Assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Section B

Very Short Answer Type Questions (6×2=12)

Q14. Student-A has to push a lighter box and student-B has push a similar heavier box on the same floor. Who will have to apply a larger force and why.

Ans: Student B will have to apply larger force than student A because according to the laws of limiting friction, the force of friction increases with increase in the mass of bodies in contact.

Q15. Why do new automobiles tyres have deep grooves?

Ans: New Automobile tyres have deep grooves because it increases the friction between the road and the tyre and stops the automobile from skidding on the road.

Q16. Give two differences between a zygote and a foetus.

Ans:

Zygote	Foetus
It is formed by fusion of sperm and egg	It is formed by division of zygote
It is single celled	It has many cells
No body parts can be seen	Body parts can be seen

Q17. Keeping in view the Figure 1. What will be the angle of incidence when the sum of angle of incidence and reflection is 100⁰?

Ans: Sum of <I and <r = 100⁰

We Know, ,<I = <R

So,

<I = 50°

<R = 50°

Q18. What are various characteristics of image formed by a plane mirror?

Ans: The Various characteristics of image formed by a plane mirror are:

1. The Image is Virtual and Erect

2. The Image is of the same size as that of object

3. The image is as far behind the mirror as the object

4. The image undergoes lateral inversion

Q19 What happens when

I. Dilute sulphuric acid is poured on a copper plate.

Ans: When Dilute Sulphuric acid is poured on a copper plate, No reaction takes place.

Hint: Copper is Less reactive than Hydrogen and cant replace it from SO4

II. Iron nails are placed in copper sulphate solution.

Write word equations of the reactions involved.

Ans: When Iron Nail is placed in Copper sulphate solution, It replaces Copper to form Iron sulphate.

Fe + CuSO4 ………> FeSO4 + Cu

Section C

Short Answer Type Questions (5×3=15)

Q20. Lightning and thunder take place in the sky at the same time and at the same distance from an observer. Lightening is seen earlier and thunder is heard later. Explain why?

Ans: Lightening is the form of Light energy while thunder is sound energy. Since, Light travels very fast than sound. So the Lightening is seen earlier and thunder is heard later.

Q21. A child studying in a coastal region test the drinking water and also the sea water with his tester. He finds that the compass needle deflects more in the case of sea water. What are the reasons?

Ans: Sea water contains many dissolved salts and ions which increase the conductivity of the solution and hence more current flows through it.

Q22. Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Ans: Asexual reproduction is the type of reproduction in which only single parent is involved. In this type of reproduction no gamates are formed.

It is of many types such as:

Binary Fission: In this, one singke cell divides into two daughter cells. e.g., Amoeba

Budding: In this, Bud grows on the surface of organisms which develops into new organism e.g., Hydra.

Q23. How is excessive accumulation of carbon dioxide in the atmosphere related with global warming?

Ans: Carbon Dioxide is a green house gas and traps more and more infra-red radiations coming from the sun. More Infra-red radiations leads to increase in temperature. Hence, it causes Global warming.

Q24. What are antibiotics? What precautions must be taken while taking antibiotics?

Ans: Antibiotics are the chemical substances produced by microorganisms that kill other microorganisms.
The antibiotics are used as medicine.
They were first discovered by Alexander Fleming.

Precautions:
1. Antibiotics should be taken only when doctor advises.
2. Full course of antibiotics should be taken.

Section D

Long Answer Type Questions (2×5=10)

Q25. Make Sketches of animal cell and plant cell. State two differences between them.

Ans:

Animal Cell	Plant Cell
Cell wall is absent	Cell wall is present
Chloroplast is absent	Chloroplast is present
Small vacuoles are present	Large vacuoles are present

Q. 26: “Cells are basic structural units of living organism”. Explain?

Ans: Cells are the smallest unit of life and are capable of all living functions. They are the building blocks of life. This is the reason they are called to as "the basic structural and functional unit of life".

Q27. Harshit a student of class 8th is observing certain changes in his body like hoarness in voice. He also observes that these changes are taking place in all his classmates who are boys and these changes are different from his classmates who are girls. These changes mark the onset of a certain stage. What this stage is called and explain the changes associated with it.

Ans: These changes are normal and occur at the onset of a stage called Puberty.

Puberty is a stage which starts at the age of 9 and lasts till 19.

The various changes associated with puberty are:

1. Change in voice

2. Increase in height and weight

3. Growth of body hair

4. Development of shoulders in boys

5. Development of breasts in girls

6. Release of gamates in both.

Q.28: Duhan observes his grandmother scolding his aunt every day for giving birth to three baby girls instead of a boy. Duhan immediately stood up and told his grandmother that giving birth to a boy or a girl is not in her hands and there is a scientific mechanism behind it. Explain the mechanism which makes a fertilized egg develop into a boy or a girl.

Ans: It is true that giving birth to a boy or a girl is not in her hands and there is a scientific mechanism behind it.

Males produce sperm which may contain either X chromosome or Y chromosome

Females produce eggs, each of which contain X chromosome.

When the sperm with X chromosome fertilizes egg, the zygote has XX chromosomes and develops into Girl.

When the sperm with Y chromosome fertilizes egg, the zygote has XY chromosomes and develops into Boy.