CBSE Class 10 Science Chapter 14 Sources Of Energy Very Short Answer Questions

CBSE Class 10 Science Chapter 14 Sources Of Energy Very Short Answer Questions

Question 1. Name the chemical compound that is added to LPG to detect its leakage.
Answer: Ethyl mercaptan (C₂H₅– SH)

Question 2. Name some devices for harnessing solar energy.
Answer: Solar cookers, solar heaters, and solar cell panels, are the devices that harness solar energy directly into heat or electricity.

Question 3. Name the greenhouse gases.
Answer: CO₂, CH₄

Question 4. State two merits of hydroelectricity.
Answer: Hydroelectricity is a clean and renewable energy source. This natural renewable energy can be stored in high-level reservoirs and can be used whenever required which is not the case with wind energy and solar energy.

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Question 5. Which out of biogas and LPG has a lower calorific value?
Answer: Biogas has a lower calorific value.

Question 6. What kind of energy transformation takes place at a thermal power station?
Answer: Chemical energy into electrical energy.

Question 7. Name the major constituent of natural gas.
Answer: Methane

Question 8. How is slurry left over after the generation of biogas in the Gobar gas plant used?
Answer: As a manure.

Question 9. Why are gaseous fuels preferred to solid fuels in chemical industries?
Answer: Gaseous fuels are preferred because

1. They can be transported easily through pipelines.
2. They leave no ash on burning.
3. They burn completely and cause less pollution than solid fuels.

Question 10. Where is natural gas usually found?
Answer: Natural gas is usually found over petroleum deposits deep under the surface of the earth.

Question 11. Write the characteristic features ofthe micro-organisms which help in the production of biogas in a biogas plant.
Answer: The micro-organisms are anaerobic bacteria that break down organic matter anaerobically and produce biogas.

Question 12. Name two combustible components of biogas.
Answer: Methane (CH4) and hydrogen (H2)

Question 13. Mention the minimum wind velocity required for obtaining electric power with a windmill generator.
Answer: The wind speed should be higher than 15 mph.

Question 14. What are the causes of acid rain?
Answer: Acidic oxides of carbon, nitrogen, and sulfur get dissolved in water during rain and cause acid rain.

Question 15. Blowing wind carries kinetic energy. Mention the two factors that cause the wind to blow.
Answer: Unequal heating of the landmass and water bodies by solar radiation generates air movement and causes wind to blow.

Question 16. Name the reaction responsible for large energy production in the sun.
Answer: Nuclear fusion.

Question 17. What is geothermal energy?
Answer: The heat from inside the earth heats the water below the surface. This energy with hot water below the earth is called geothermal energy.

Question 18. Give two limitations in the use of solar cells.
Answer: Limitation of solar cells

1. The efficiency of solar cells is low.
2. It produces direct current.

Question 19. Mention any one reason due to which most of the thermal powerplants are set up near coal or oil fields.
Answer: Transportation of electricity is more efficient than transporting coal or petroleum over some distance.

Question 20. List two forms of energy in which solar energy manifests itself in one answer:
Answer: Ocean thermal energy Wave energy

Question 21. Give one example of each renewable and non-renewable source of energy.
Answer: Renewable- Solar energy, wind energy. Non-Renewable- Coal, petroleum.

Question 22. Why are solar cookers painted black?
Answer: They are painted black to ensure maximum heat absorption, as black surfaces are good absorbers of solar radiation.

Question 23. In which form can cow dung be used to maximum advantage?
Answer: Cow dung is put to maximum advantage by using it to produce biogas.

Question 24. What is calorific value?
Answer: The heat generated by burning the unit mass of a fuel is called its calorific value.

Question 25. A student constructed a box-type solar cooker and covered it with a glass plate. Write the purpose of a glass plate in a cooker.
Answer: It is used to trap solar heat inside the solar cooker.

Question 26. The use of dry wood as domestic fuel is not considered as good. State two reasons for it
Answer: Lots of smoke on burning. Lots of residue after burning.

Question 27. The construction of dams submerges large areas of forests, how does this contribute to the greenhouse effect?
Answer: Submerged forests decompose anaerobically, this produces methane which is a greenhouse gas.

Question 28. What is the main purpose behind the use of a mirror in solar cookers?
Answer: A mirror in a solar cooker acts as a reflector of sunlight into the box and thus gives a higher concentration ofheat rays at a point.

Question 29. Name the chief component of solar cells. What energy conversion takes place in a solar cell?
Answer: Silicon. It converts solar energy into electrical energy.

Question 30. What steps would you suggest to minimize environmental pollution caused by the burning of fossil fuels?
Answer: Use of smokeless appliances.