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ASSIGNMENT
1. Fill in the blank spaces by choosing the correct words from the list given below :
List : gaseous, mechanical, photovoltaic, desirable, renewable, anaerobic, nuclear,
dependable, bio, sulphur dioxide.
(a) Biomass is a .............................. source of energy.
(b) CNG is an example of a .............................. fuel.
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(c) The fermentation of animal dung is brought about by .............................. bacteria,
in the absence of air.
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(d) Acid rain is caused by .............................. gas present in air due to pollution.
(e) The generator converts .............................. energy into electric energy.
(f) Biomass can be added to cow dung in the generation of .............................. gas.
(g) A .............................. cell converts solar energy into electric energy.
(h) .............................. energy is obtained by splitting uranium atoms with slow
moving electrons.
(i) The wind energy is not very .............................. as the wind does not blow all the
time at the same speed.
(j) Electricity is the most .............................. form of energy.
2. Statements given below are incorrect. Write the correct statements.
(a) Box type solar cooker can raise the temperature of its interior upto 400°C.
(b) Solar heating devices are very fast in comparison to other heating devices.
(c) The process due to which nucleus of uranium splits, is called nuclear fusion.
(d) Fast moving neutrons are used in splitting nucleus of uranium.
(e) Excessive burning of fossil fuels is cooling the earth’s atmosphere.
(f) The armature of an electric generator converts electric energy into mechanical
energy.
(g) Nuclear energy is the cleanest form of energy.
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(h) A photovoltaic cell converts electric energy into light energy.
(i) Solar panels are used to run wrist watches.
3. Write ‘True’ or ‘False’ in front of statements given below :
(a) Wood is a non-renewable source of energy.
(b) In photovoltaic cells, light energy is converted into electric energy.
(c) Tidal power plants can be constructed near the mouth of narrow bays.
(d) Wind is caused due to uneven heating of the surface of the earth.
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(e) Solar cells can be used to operate big electrical devices.
(f) In wind farms, the potential energy of wind changes into electric energy.
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(g) Kerosene oil is a renewable source of energy.
(h) Nuclear energy is highly dangerous
(i) Hot spots are the places on the Earth, where sun shines more brightly.
(j) Fossil fuels are the main cause of atmospheric pollution.
4. Tick (
) the most appropriate answer.
(a) The device which directly converts solar energy into electric energy, is :
(i) solar heater
(iii) solar cell
(ii) solar furnace
(iv) solar water heater
(b) The energy which directly changes into electric energy, in solar cell is :
(i) heat energy only
(iii) heat and light energy
(ii) light energy only
(iv) none of these
(c) The kind of energy present in fossil fuels, is :
(i) heat energy
(iii) chemical energy
(ii) mechanical energy
(iv) geothermal energy
(d) The ultimate source of hydroelectric energy, is :
(i) potential energy of water
(iii) solar energy
(ii) kinetic energy of water
(iv) magnetic energy
(e) The renewable source of energy amongst the following, is :
(i) coal
(iii) natural gas
(ii) petrol
(iv) solar energy
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(f) The non-renewable source of energy amongst the following, is :
(i) wind energy
(iii) solar energy
(ii) hydel energy
(iv) chemical energy
(g) The splitting of heavy nucleus of an element with the release of energy is called :
(i) combustion
(iii) fission
(ii) fusion
(iv) photosynthesis
(h) The gas which is obtained from biomass, is :
(i) LPG
(ii) CNG
(iii) Biogas
(iv) hydrogen
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(i) Bhakhra-Nangal hydel project is situated in the state of :
(i) Gujarat
(ii) Orissa
(iii) Punjab
(iv) Karnataka
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(j) The energy possessed by moving water is :
(i) potential energy
(ii) kinetic energy
(iii) geothermal energy
(iv) hydroelectric energy
5. Find the odd one out. Give a reason for your choice.
(a) flowing water, tidal waves, coal, hard blowing wind.
(b) liquefied petroleum gas, biogas, compressed natural gas, hydrogen gas.
(c) farm residues, animal dung, wood, coal.
6. (a) Define renewable sources of energy.
(b) Name four renewable sources of energy.
(c) Define non-renewable sources of energy.
(d) Name two important non-renewable sources of energy.
7. Pick out renewable and non-renewable sources of energy from the following list :
List : (i) Geothermal energy, (ii) Petrol, (iii) Coke, (iv) Tidal energy, (v) Hydel energy,
(vi) Biomass, (vii) CNG, (viii) Wind energy.
8. Why are coal and petroleum products called non-renewable sources of energy?
9. How does solar energy change into chemical energy?
10. Why is it important to harness solar energy?
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11. State four traditional uses of solar energy.
12. (a) How much solar energy is received per sq. metre, per unit time on the surface of
earth?
(b) State three ways of enhancing the collection of solar energy.
13. Answer the following questions regarding box type solar cooker.
(a) Why is its interior surface painted black?
(b) Why is its lid made from double walled glass sheets?
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(c) Why is a plane mirror reflector provided in the cooker?
(d) State average temperature attained by this cooker.
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14. Give three differences between box type solar cooker and spherical reflector type solar
cooker.
15. State three commercial uses of solar water heater.
16. What is a solar power plant?
17. (a) What do you understand by the term photovoltaic effect?
(b) (i) What is a solar panel?
(ii) State four uses of solar panel.
18. (a) Explain how wind energy can be converted into electric energy.
(b) Why is wind energy undependable? Give two reasons.
(c) State two advantages of wind energy.
19. State all the energy changes taking place at the hydroelectric dam.
20. (a) State two limitations in the generation of hydroelectricity.
(b) State two advantages of hydel power.
21. (a) What is tidal energy?
(b) Briefly describe, how is tidal energy harnessed?
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22. (a) Briefly describe how is nuclear energy converted into electric energy.
(b) State two dangers associated with generation of electricity from nuclear power
plants.
23. (a) What do you understand by the term anaerobic fermentation?
(b) Answer the following questions regarding biogas plant.
(i) Name two raw materials used.
(ii) Name the constituents of biogas.
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(iii) Why large amount of water is added to cow dung?
24. (a) What do you understand by the term air pollution?
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(b) How is air polluted by the activities of human beings? Give at least three reasons.
(c) State the problems created by the following pollutants :
(i) Dust and smoke particles
(ii) Carbon monoxide
(iii) Sulphur dioxide
(d) State briefly, three ways of reducing air pollution.
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