CBSE Set Qa1 Science Class X 1996 Sample Test Papers For Class 10th for students online

Science Class X (CBSE)
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General Instructions :
(i)   All questions are compulsary.
(ii) Question number 1 to 10 are very short answer question,carrying 1 mark each.They are to be answered in one or two sentences.
(iii) Question number 11 to 20 are short answer questions,each carrying 2 marks. Answer to them should not exceed 40 words each.
(iv)  Question numbers 21 to 30 are also short answer questions,each carrying 3 marks. Answer to them should not exceed 60 words each.
(v) Question numbers 31 to 33 are long answer questions,each carrying 5 marks. Answer to them should not normally exceed 100 words each.

Q 1. What will be the effect of increase in the amount of carbon dioxide in the atmosphere on the Average temparature of earth ?
Ans1. The temperature will rise due to the green house effect.

Q 2. A chemical factory in a village discharges its waste, rich in nitrogen compounds, into a pond. How will it affect the growth of phytoplanktons?
Ans2. The phytoplanktons will grow enormously leading to eutrophication of the pond.

Q 3. In the following food chain, plants provide 2000 J of energy to Rats. How much energy will be available to Hawks from the snakes?
Plants Rats Snakes Hawks
the energy available to hawks is
Ans3. 20 J.

Q 4. The formulae of two organic acids X and Y are C₁₀H₂₁ COOH and C₁₉H₃₉ COOH. Which of them exists in liquid state at room temperature?
Ans4. C₁₀H₂₁ COOH. exists in liquid state at room lamp.

Q 5. Why is the outer part of the candle flame blue?
Ans5. The outer part of the flame is blue because the supply of oxygen is adequate there and there are no unburnt carbon particles.

Q6. Fermentation of sugar solution with enzymes is being carried out in a vessel at 20°C - 30°C in the presence of air. Which organic compound will be produced in this process?
Ans6. Ethanoic acid.

Q7. A doctor examined a patient and advised him to take more lemon, orange and amla in his diet. Write any two symptoms that the doctor might have noticed in the patient.
Ans7. (1) Swelling and bleeding of gums.
(2) Loosening of the teeth.

Q8. A constellation having seven prominent stars is visible during the winter. Name the Constellation.
Ans8. Orion.

Q9. An element X on reacting with oxygen forms an oxide X₂O. This oxide dissolves in water and turns blue litmus red. State whether element X is a metal or a non-metal.
Ans9. A non-metal because the oxide is acidic.

Q10. The number of protons in the nucleus of an atom of an element of mass number 238 is 92. What will be the number of neutrons in its isotope of mass number 235 ?
Ans10. The isotopes have same number of protons but different numbers of neutrons.

Mass number = number of protons + number of neutrons

number of neutrons = 235 - 92 = 143

Q11. Galaxies A and B are x light years apart while C and D are 1.5x light years apart. In which pair will the two galaxies be moving faster away from each other ? Give reasons for your Answer ?
Ans11. The speed at which galaxies move away is directly proportional to the distance between them. Thus C and D would be moving away from each faster than would be moving A and B.

Q12. Why is charcoal considered a better fuel than wood? Give four reasons.
Ans12. 1. Charcoal has a higher calorific value than wood.
2. Charcoal does not leave behind as much ash as does wood.
3. Charcoal is a compact fuel as compared to the woods and thus its transportation and storage is easier.
4. Charcoal produces less smoke than does wood.

Q13. In textile mills a white substance having a strong smell of chlorine is used to remove yellowness of white clothes. Identify the substance. How is it prepared? Write
chemical equation of the reaction involved.
Ans13. The substance is "Bleaching Powder (CaOCl₂)". or Ca(OC1)C1
It is prepared by passing chlorine gas in slaked lime.

Ca(OH)₂ + Cl₂ CaOCl₂ + H₂O

Q14. A water pump can lift 500 kg of water to a tank situated at a height of 10 m in 10 s.
Calculate the power of the pump. [ g = 10 m/s²].
Ans14. given,
Mass of water lifted,m = 500 kg
acceleration due to gravity,g = 10 m/s²
height to which water is to be lifted,h = 10 m
time in which water gets lifted = 10 s

Potential energy used to lift water = m x g x h
= 500 x 10 x 10 J

              Energy
Power
              Time

              50,000 J
Power
              10 s
            = 5000 W

            = 5 kW
Ans. Power of the pump is 5 kW  

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Q15. How is an ester prepared in the laboratory? Write its one use in daily life.
Ans15. Ester is prepared by reacting organic acids with alcohols in the presence of sulphuric acid.
                                  H₂SO₄
CH₃COOH + C₂H₅OH CH₃COOC₂H₅ + H₂O
In daily life, esters are used in perfumes and fragrances.

Q16. A gardener by mistake has sown seeds of sunflower too deep in a wet fertile soil. How will this practice influence the production of sunflower crop? Give two reasons for your answer.
Ans16. The yield of the crop will be poor because the extent of germination of the seeds of sunflower wil be very low. The reasons are:
1. the seeds and the seedlings will not get enough oxygen too deep in the wet soil.
2. even if the seeds germinate, the seedlings will not be able to come out on the surface of soil.

Q17. Waste of which of the following two materials is more polluting - polythene or paper? Give reasons for your answer.
Ans17. Wastes of polythene are more polluting because it is not bio-degradable and hence remains undegraded for too long in the environment. It clogs the drains, spoils the underground water quality and poses dangers for animals' lives.

Q18. List four conditions for life to exist on a planet.
Ans18. The essential requirements for the life to originate on any planet is:
(i) presence of elements like: C, N, O, H, P, S, and O;
(ii) a moderate temperature range, so that the life permitting reactions could sustain;
(iii) presence of a liquid medium like water to transport nutrients;
(iv) a protective blanket around the earth to prevent harmful radiations from entering the atmosphere.

Q19. What are synthetic detergents? Give one example of a synthetic detergent. Write its two advantages over soaps.
Ans19. Synthetic detergents are two-headed molecules one end of which are water repelling and the other water attracting. The water repelling end is hydrocarbon from coal or petroleum; and the water attracting part is a sulphate or a sulphonate group.

Sodium dodecylsulphate is a synthetic detergent.

The advantages of detergents over soaps are:
1. Have more cleaning capacity and are milder to the hands,
2. Lather well even in harder water than do the soaps.

Q20. What is the principle of working of solar heater ? Write two major drawbacks of all solar heating devices.
Ans20. Solar cooker works on the principle of solar heat warming the enclosed air in the solar cookerbox due to heating effects of the IR. When the sun rays fall on the box, the black inner surface of the solar cooker absorbs the solar heat energy and becomes hot. This heat cooks the food material
kept in the container.The black surface, the insulator material, the glass sheet and the mirror maximise the heat absorption, heat retention, and minimise the heat loss.

Two major drawbacks of all solar heating devices are:
1. Dependence on the availability of bright sun-light and hence unpredictability in the rainy and foggy weathers.
2. They have to be adjusted intermittently to keep them facing them sun.

Q21. What causes the wind to blow ? Explain the principle of working of a windmill. State two advantages of using wind energy.
Ans21. The difference in the temperatures at the equatorial and polar regions cause a flow of air from the poles to the equator. This flow of air gets disturbed by the rotation of the earth as well as local conditions, which result in wind. The wind energy is the kinetic energy associated with movement of large masses of air. When the blowing wind strikes across the blades of a windmill it exerts a force which rotates its blades.

Advantages of using wind energy are:
1. It helps to conserve the non-renewable fossil fuels.
2. When wind energy is converted to electricity, it does not cause environmental pollution.

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