CBSE Class 10 science Important Questions Chapter 14 – Sources of Energy

2 Mark Questions

1. Hydro power is a renewable source of energy. Justify.

Ans. Hydro power is a renewable source of energy because if is derived from the renewable source of energy i.e. Sun.

2. Write two qualities of an ideal source of energy?

Ans. The tow qualities of an ideal source if energy are-

(i) It does not cause environ mental pollution-

(ii) Economical.

3. What are the advantages of nuclear energy?

Ans. Advantages of nuclear energy-

(i)A small quantity of fuel provides large amount of energy.

(ii)The nuclear fuel once inserted in nuclear power plant gives large amount of energy for a longer period of time.

4. Name two activities in our daily life in which solar energy is used?

Ans. (i) For cooking food using solar cookers.

(ii) For drying clothes and food grains.

5. Write two advantages of using solar cooker?

Ans. (i) Pollution free

(ii)Nutrition value of food is preserved when food is cooked inside a solar cooker.

6. Suggest two ways to reduce energy consumption?

Ans. (i) Fuels used for burning must be extinguished as soon as their use is over.

(ii) Bulb, tubes, fans and other electrical appliances must be switched off as you leave your room.

7. What is geothermal energy? Write its advantages?

Ans. The heat energy obtained from hot rocks present in earth’s crust of geo thermal energy.

The advantages of geo thermal energy are-

(i) Environment friendly.

(ii) Cost of converting geo-thermal energy into electricity is less.

8. Why are many thermal power plants set up near coal or oil fields?

Ans. The thermal power plants are usually set up near coal or oil fields so that the fuel is easily available and the problem of air pollution while transporting the fuel may be minimized.

9. What is a good fuel?

Ans. A good fuel is that which release more heat on burning, is easily available at the economical rate and do not cause environmental pollution.

10. If you could use any source of energy for heating your food, which one would you use and why?

Ans. We shall use LPG/PNG gas or electricity for heating your food because these are pollution free and have high calorific value.

11. What kind of mirror –concave or convex or plain –would be best suited for use in a solar cooker? Why?

Ans. Large size concave mirrors are best suited for use in solar cooker, because they focus large amount of solar radiation on a small surface area so temperature will rise quickly.

12. Can any source of energy be pollution free? Why or why not?

Ans. No, source of energy is completely pollution free. A source of energy to be pollution free if neither it causes any pollution during its actual operation nor there any pollution during assembly of devices utilizing that source of energy. Solar cell device may have caused some pollution.

13. Hydrogen has been used as rocket fuel; would you consider it a clear fuel than CNG? Why of why not?

Ans. Hydrogen can be considered a cleaner fuel because its burning produces water vapor which is non-polluting. However, due to explosive nature of hydrogen, its storage and transportation is difficult.

14. The cost of production of electricity in a thermal power station located in Bihar/Tharkliand/Orissa is less than in Gujarat/Maharashtra. Do you agree? Justify your answer.

Ans. It is because coal is available in Bihar/Jharkhand/Orissa locally, whereas it has to be transported for any thermal power plant in Gujarat/Maharashtra.

15. Which of the following sources of electricity involves more running expenses and why? Thermal power station, Hydro power station, solar cells or Geothermal source.

Ans. Thermal power stations involve more running cost due to continuous use of coal.

16. Why is there so much emphasis on changing over from petrol/diesel driven automobiles to CNG-driven vehicles?

Ans. CNG on burning produces only carbon dioxide and water. It does not produce smoke.

-It does not leave unburnt hydrocarbons, lead particulates etc.

17. Which of the following is not an example of the biomass energy source?

(a) Wood (b) gobar gas (c) atomic energy (d)coal.

Ans. Atomic energy is not an example of biomass energy source.

18. How is the supply of electricity maintained in a windmill when there is no wind? In a solar panel when there is no sun?

Ans. In both the cases, the electricity generated is stored in a battery. This battery provides electricity when there is no wind in the case of a windmill and no sun in the case of a solar panel.

19. Can any source of energy be pollution-free? Why or why not?

Ans. No source of energy can be called pollution-free, because the use of any source of energy disturbs the environment in one way or the other. The actual source of energy may be pollution-free, but the assembly of the device might have caused some damage to the environment. So, in absolute sense, no source of energy can be called pollution-free.

20. Though a hot iron emits radiation, yet it is not visible in the dark, why?

Ans. Hot iron emits infra-red rays and these are not visible to our eyes.

21. Define: OTE (ocean thermal energy).

Ans. The energy available due to the difference in the temperature of water at the surface of the ocean and at deeper levels is called OFF.

22. Give two ways in which animal dung can be used as fuel. Which way is better and why?

Ans. As dung cake and as Biogas. Biogas is better because it spreads less pollution and has more calorific value.

23. The wind velocity at three places A, B and C are 5Km/hr, l5Km/hr, 10Km/hr respectively. Which is the most suitable place for installing wind mill & why?

Ans. B, Maximum velocity required is 15km/h. At lower speed it will not work. At very high speed it may break the blades.

24. What are two advantages of charcoal over wood as fuel?

Ans. High calorific value & pollution free

25. Mention any two reasons, why wood is not preferred as fuel.

Ans. (i) Burning wood causes pollution

(ii) Excess use of wood would cause deforestation.