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

CBSE Chapter 14 Sources Of Energy Short Question And Answers

Question 1. If you could use any source of energy for heating your food, which one would you use and why?
Answer: We would prefer to use cooking gas like LPG or PNG or electricity. It fulfils many ofthe criteria of a good fuel, most importantly its ignition temperature, good calorific value and non-pollution characteristics.

Question 2. What are the disadvantages of fossil fuels?
Answer: There are the following disadvantages of fossil fuels like coal and petroleum:

1. Burning of coal or petroleum causes air pollution.
2. Acidic oxides like oxides of carbon, nitrogen and sulphur are released on burning fossil fuels. These oxides lead to acid rains, which affect our water and soil resources.
3. Carbon dioxide gas also causes a greenhouse effect in the atmosphere.
4. Fossil fuels are non-renewable sources of energy.

Question 3. Why are we looking at alternate sources of energy?
Answer: Fossil fuels are non-renewable sources of energy and their reserves are limited. Besides, these cause lots of pollution. Hence, we need to conserve them. If we continue consuming these sources at the same rate as presently, we may soon run out of energy. To avoid such a situation we are looking at alternate sources of energy.

Read and Learn More CBSE Class 10 Science Short Answer Questions

Question 4. How has the traditional use of wind and water energy been modified for our convenience?
Answer: To use the kinetic energy of flowing water or the potential energy of water at a height, large dams have been built in hilly regions to store huge amounts of water at a height.

The stored water from the level in the dam is carried through pipes to the turbine at the bottom of the dam and runs the hydropower plant. Similarly, the wind energy is used to generate electricity. For this purpose, the rotatory motion of the windmill is used to turn the turbine ofthe electric generator.

Question 5. What kind of mirror—concave, convex or plain—would be best suited for use in a solar cooker? Why?
Answer: Large-size concave mirrors are best suited for use in a solar cooker because they focus large amounts of solar radiation on a small surface area so the temperature will rise quickly and appreciably.

Question 6. What are the limitations ofthe energy that can be obtained from the oceans?
Answer: Energy from the oceans can be obtained in the form of tidal energy, wave energy and ocean thermal energy.

But these energy sources suffer from the following limitations:

1. There are very few locations where dams to utilise tidal energy can be built.
2. The cost of installation of powerhouses is extremely high and the efficiency of plants is comparatively small.
3. Power plants built in oceans or at seashores will need continuous maintenance as the chances of corrosion are extremely high.

Question 7. What is geothermal energy?
Answer: Geothermal energy is the heat energy present inside the earth in certain regions called ‘hot spots’. Due to geological changes, molten rocks formed in the deeper hot regions of Earth’s crust are pushed upwards and are trapped in hot spots. When underground water comes in contact with the hot spot, steam is generated. This steam is the source of geothermal energy.

Question 8. What are the advantages of nuclear energy?
Answer: The main advantages of nuclear energy are as follows:

1. For a given mass of fuel consumed the amount of energy released is extraordinarily large.
2. Nuclear power plants can be designed and constructed at any convenient place.
3. If proper precautions are taken while running nuclear power plants, a major fraction of energy needed can be obtained from nuclear energy sources which is being done by many developed countries.

Question 9. Can any source of energy be pollution-free? Why or why not?
Answer: We shall call a source of energy to be pollution-free if neither it causes any pollution during its actual operation nor there is any pollution during assembly of devices utilising that source of energy. As an example, the solar cell is a clean and pollution-free source by itself but assembly of solar cell devices may have caused some pollution.

Question 10. Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Answer: Hydrogen can be considered a cleaner fuel because its burning produces only water vapour which is non-polluting. However, due to the explosive nature ofhydrogen, its storage and transportation are difficult.

Question 11. Name two energy sources that you would consider to be renewable. Give reasons for your choices.
Answer: Solar energy, wind energy, ocean energy etc., are renewable sources of energy for the following reasons:

1. These forms of energy are available in plenty of our natural environment in the form of continuous currents of energy.
2. These energy sources will not be depleted so long as the present solar system exists.

Question 12. Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Answer: Coal and petroleum are two exhaustible sources of energy. These fuels were formed millions of years ago and there are only limited reserves. If we continue To Use Them As At Present, These Reserves Will Be Exhausted Soon.

Question 13. Compare and contrast fossil fuels and the sun as direct sources of energy.
Answer: The comparison between fossil fuels and the sun as a direct source of energy is as follows:

Question 14. Compare and contrast biomass and hydroelectricity as sources of energy.
Answer: Differences between Biomass and Hydroelectricity:

Question 15. What are the limitations of extracting energy from:

1. The Wind1?
2. Waves?
3. Tides?

Answer:

Limitations of extracting energy from the wind are as given below:

1. Wind energy farms can be established at those places only, where the wind blows for the greater part of a year.
2. For wind energy, the wind speed should be higher than 15 km/h.
3. A wind farm requires a large area and the initial cost of establishment of a farm is high.
4. It requires a high level of maintenance because the tower and blades are exposed to rain, sun, storm, etc.
5. It requires a backup with batteries for periods when there is no wind.
6. Limitations of extracting wave energy are as follows:
7. Wave energy can be harnessed by trapping the sea waves in a dam. Only very few suitable sites exist where dams can be constructed.
8. It is not a continuous and reliable source of energy.
9. It is extremely costly, cumbersome and difficult to maintain a power unit based on wave energy on a sustained basis.
10. The limitations of extracting tidal energy are the same as for wave energy.

Question 16. On what basis would you classify energy sources as

1. Renewable And Non-Renewable?
2. Exhaustible And Inexhaustible?
3. Are the options given in and the same?

Answer: Renewable sources of energy are those sources which can be regenerated again. Nonrenewable sources of energy are those sources which would get depleted someday and cannot be regenerated.

1. Exhaustible sources of energy are those which will get depleted someday and cannot be regenerated. Inexhaustible sources of energy are those which can be regenerated again due to some continuing or repetitive currents of energy.
2. Options are given in and are the same. A non-renewable source is an exhaustible source. A renewable energy source is an inexhaustible source.

Question 17. What are the qualities ofan ideal source of energy?
Answer: The qualities of an ideal source of energy are as given below:

1. It should be an easily accessible, inexhaustible, renewable source of energy and the cost of harnessing energy should be reasonably small.
2. The energy obtained from the source should be easily stored and transferred from one place to another place.
3. The energy source should not cause directly or indirectly any sort of pollution or degradation of the environment.
4. The technology for harnessing energy from a given source should be easily available, cheap and efficient.

Question 18. What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?
Answer: Advantages of a solar cooker

1. There is no cost of fuel.
2. It is environment friendly and there is no residue like ash etc.
3. Cooking is hygienic and nutritious.
4. Disadvantages of a solar cooker
5. The cooking is slow. It takes 2-3 hours to attain a temperature of100°C-140°C on a sunny day.
6. It does not work on a cloudy day.

Question 19. What are the environmental consequences of the increasing energy demand? What steps would you suggest to reduce energy consumption?
Answer: Ronment in some way or the other. Either it would cause more pollution or cause environmental damage. Development and consumption of energy would go together. Therefore we should concentrate more on finding better and alternative sources of energy.

When looking for alternative sources, the following points should be kept in mind:

1. Ease and cost of extracting energy from the source,
2. The efficiency of the available technology.
3. Environmental impact of using that source

Answer:

Question 20. Define fuel. List any two characteristics that you would look for in a good fuel.
Answer: Fuel is a source of energy that we choose for doing some work.

1. Amount of ofheat released by it on burning per unit mass
2. Easy storage and transportation
3. Economical
4. Pollution-free.

Question 21. The waste materials collected from a market complex are scrap paper, thermocol, vegetable waste, tin cans and glass bottles. Which ofthese can be used for producing biogas? Mention three advantages of converting these into biogas rather than burning them.
Answer: Scrap paper and vegetables can be used to produce biogas. Converting these into biogas has the following advantages:

1. It produces cheap and valuable fuel for which there is a great demand.
2. It utilises those substances which would, otherwise be wasted and, require space for its safe dumping.
3. If this waste is left as such then it will be decomposed by microorganisms. This
   results in the release of harmful gases which increases environmental pollution.

Question 22. Compare the advantages of generating energy from biomass to getting it from hydropower plants.
Answer:

Question 23. What do you mean by a clean fuel? Is an absolute clean fuel available?
Answer: A clean fuel is that which does not cause environmental damage when used to produce energy.

No fuel is clean. Some environmental damage is caused directly or indirectly by the fuel. We can only call one source less or more cleaner than the others.

Question 24. Mention the advantages and limitations of wind energy.
Answer: Advantages:

1. It IH used to propel sailboats.
2. It is used to drive windmills which further operate water lifting, pumps and flourmills.
3. Aeroplanes use this energy for their upward and downward movements
4. It is used for flying engineless aeroplanes called gliders and for generating electricity.
5. It is free of cost and does not cause any pollution.

Limitations:

1. It is not available at all times.
2. It requires a very large area of land.
3. It is not possible to have a windmill everywhere, as to run it, the minimum wind
   speed of 15 km/h is required.

Question 25. Why is biogas plant considered to a be boon to the farmers? Give reason.
Answer: Biogas plants are considered to be a boon to the farmers because farmers can get clean fuel which does not produce any kind of smoke and pollution as compared to dried dung cakes.

Question 26. List any four reasons why we need to look for alternate sources ofenergy.
Answer: Pollution due to fossil fuels, exhausting fuel reserves, increasing need, replenishment is not easy.

Question 27. Explain why obtaining energy from nuclear fusion reactions is preferable to obtaining energy from nuclear fission reactions. Give two reasons.
Answer: Obtaining energy from nuclear fusion reactions is preferable to obtaining energy from nuclear fission reactions because:

1. For a given mass, the energy released from nuclear fusion is much larger than the energy released from nuclear fission.
2. Nuclear waste in nuclear fission is radioactive. Its disposal is a big challenge. There is no such difficulty in nuclear fusion.

Question 28. Why is tidal energy not likely to be a potential source of energy?
Answer: The harnessing of tidal energy poses many problems. The rise and fall of water during tides is not high enough to generate electricity on a large scale. There are very few sites that are suitable for building dams. It is for these reasons that tidal energy is not likely to be a major source of energy.

Question 29. “Electricity generated by the water stored in a dam can be considered to be another form of solar energy.” Explain describing the series of energy transformations in sequence taking place during the process.
Answer: Given below is the sequence of energy transformations that take place in the generation of electricity from the water stored in a dam.

Solar energy changes into potential energy (PE) of water vapour rising in the atmosphere, during the evaporation of water from rivers, seas, oceans and other water masses. These water vapours form clouds and cover mountains with snow.

1. When clouds burst into rain or the snow melts, their PE changes into kinetic energy of water flowing into streams and rivers.
2. When this flowing water is stored in a dam, its KE changes into PE.
3. When water is released from the dam, its PE once again changes into KE.
4. The KE of water coming out of the dam moves turbines which generate electricity.
5. Thus, it is the solar energy which changes into electricity.

Question 30. What is natural gas? How is it formed?
Answer: Natural gas is a naturally occurring mixture of methane (approx. 85%), ethane (10%), propane (3%), and butane (2%). Other non-combustible gases like CO2, N2 and O2 may also be present in the mixture.

Natural gas is formed by the action of heat, pressure and microorganisms on buried organic matter over millions of years.

Question 31. Give two advantages ofsmokeless chulha over traditional chulha.
Answer:

1. It has more efficiency and produces less smoke
2. It is scientifically designed and consumes less fuel.
3. The complete combustion of fuel takes place in it and it has a tall chimney.

Question 32. Justify the statement ‘Hydrogen is a cleaner and better fuel than CNG’.
Answer: Yes, it is a cleaner fuel because on burning, hydrogen produces only water vapour which is non-polluting. Although it is not used in everyday life due to its explosive nature, storage and transportation problems.

Question 33. What is nuclear waste? What are the hazards of nuclear waste to living beings? How is nuclear waste disposed of?
Answer: The discarded material of the nuclear industry is called nuclear waste such as remains in the containers which are used to handle radioactive substances or radioactive products of nuclear reactions.

1. The waste material more often possesses radioactivity which emits particles capable of damaging man, animal and plant tissues.
2. Nuclear wastes cannot be destroyed by chemical or other methods. These have to be buried deep under the earth.

Question 34. A student constructed a box-type solar cooker. He found that it was not working efficiently. What could this be due to? Give any four possible mistakes in the construction and operation of the solar cooker. What maximum temperature can ordinarily be reached inside a solar cooker?
Answer: He might not have painted the box black from the inside.

1. He might not have placed the blackened sheet in the insulated part of the solar cooker.
2. He might not have attached the reflector at the right angle.
3. He might not have covered his box with a thick glass sheet. He might have used a thin glass sheet.

Question 35. Why is a floating gas holder-type biogas plant considered less advantageous than a fixed dome-type biogas plant? Give reasons.
Answer: Floating gas holder type biogas plant is considered less advantageous because:

1. A floating gas holder type biogas plant is costly as it is made of steel.
2. Gas can leak through it either due to defects in welding or due to corrosion of steel.
3. It has to be repaired and painted frequently which increases its maintenance cost.

Question 36. Why is charcoal considered to be a better fuel than wood? What are the disadvantages of converting wood into charcoal?
Answer: Charcoal is considered as a better fuel than wood because:

1. Charcoal burns easily without producing smoke.
2. It gives twice as much heat as given by the same mass of wood.
3. The disadvantage of converting wood into charcoal is that during destructive distillation of 1 kg of wood only 0.25 kg of charcoal is obtained.
4. In other words, the conversion is expensive; hence charcoal is an expensive fuel.

Question 37. Why can wind energy farms be established only at specific locations? Give reasons to support Your Answer
Answer: Wind energy farms can be set up only in locations:

1. Where the wind blows for the greater part of the year.
2. Where the wind is strong and steady and has a speed of about 16 km h-1.
3. Where large free space is available.
4. Since these conditions cannot be satisfied everywhere, therefore, wind energy farms can be set up only in specific locations.

Question 38. Why is it not possible to make use of solar cells to meet all our energy needs? State at least three reasons to support your answer.
Answer: High cost of installation.

1. Limited availability of special-grade silicon to make solar cells.
2. Unavailability of an efficient system to store electrical energy generated by solar panels.

Question 39. What are thermal power plants? Give a demonstration of how thermal energy can be converted into electrical energy.
Answer: Thermal power plants convert heat energy into electrical energy. In thermal power plants, fuels are burnt to heat water to produce steam which is designed to run the turbine to generate electricity. The class can be demonstrated as follows:

Take a tennis ball and make three silts into it. Fit three small fins of a metal sheet into these slits. Fix the tennis ball on an axle as shown so that the ball has a free rotation.

Now connect this axle to a bulb through a dynamo. Direct a jet of steam from a pressure cooker onto to fins of the ball. Soon the bulb will start glowing. It will glow till the ball is rotating with the help of steam.

Question 40. Biomass has been used as fuel since ancient times, how has it been modified to function as a more efficient fuel in the recent past?
Answer: Coal and petroleum.

Yes, it is a cleaner fuel because on burning only water vapour is produced, which is non-polluting but due to the explosive nature of hydrogen storage and transportation is difficult.

Question 41. State the principle of a reflector-type solar cooker. How is this type of solar cooker different from a box type of solar cooker?
Answer: Reflector-type solar cooker: In this solar cooker, a concave reflector or parabolic reflector is used. It concentrates the solar energy in a small region called focus and therefore quite high temperature can be produced.

This way is different from box-type solar cookers because here food materials requiring strong heating can also be cooked. It can be used for baking and frying also.

Question 42. With the help of a diagram, explain how the design of a box type of solar cooker ensures minimum loss ofheat from its inside.
Answer: The box of the solar cooker is made of-conducting material, for example, plastic or fibreglass with thick inner walls. It is covered with a glass sheet which prevents loss of longer wavelength infrared radiations from inside to outside.

Question 43. Write the composition and source of LPG. Although liquefied gas is present in the cylinder, how does it appear as a gas in the burner?
Answer: LPG contains Butane (main), Propane and Ethane. It occurs over petroleum. Some wells contain only petroleum gas.

It is present in liquid form in the cylinder because it is filled at very high pressure, therefore, it liquefies. But when it comes out of the cylinder, the pressure is released and it appears as a gas in the burner.

Question 44. State four characteristics ofan ideal fuel.
Answer: It should be cheap and easily available.

1. It should have a high calorific value and should burn smoothly.
2. It should have a moderate ignition temperature and should be easy to store, handle
   and transport.
3. It should not leave any residue and should not produce smoke and harmful products.

Question 45. Give the disadvantages of constructing big dams across the river. How does the construction of dams across the river get linked with the production of greenhouse gases?
Answer: Large areas of agricultural land and the human population get submerged.

The problem of rehabilitation of displaced people.

The vegetation which is submerged rots under anaerobic conditions, giving a large amount of methane which is a greenhouse gas.

Question 46. Electricity generated by the water stored in a dam can be considered to be another form of solar energy. Describe the series of energy transformations in sequence during the process.
Answer:

Question 47. How can the pollution caused by fossil fuels be reduced?
Answer: The pollution caused by fossil fuels can somewhat be reduced by:

Increasing the efficiency of the combustion process using various techniques to reduce the escape of harmful gases and ashes into the surroundings.

Question 48. What is a thermal powerplant? Where is preferably situated?
Answer: In thermal power plants, fossil fuel is burnt to convert water into steam which further rotates the turbines to produce electricity.

Such plants are preferably located near coal mines or oil fields and away from habitats. It is easier to transport electricity than to transport coal or petroleum.

Question 49. A student constructed a model of a box-type solar cooker. He used a transparent plastic sheet to cover the open face of the box. He found that this cooker does not function well. What could be the possible drawbacks of his model? List any four drawbacks.
Answer: He may not have used:

1. Black painted aluminium sheet.
2. Black cooking vessel to absorb heat radiation.
3. Glass sheet, which prevents the escape of heat radiation from the box instead of plastic sheet.
4. Mirror plate which reflects the sunlight to fall on the glass sheet.

Question 50. Why is there a need to harness non-conventional sources ofenergy? Give two main reasons.
Answer: Our energy demand is increasing to improve the quality of life and population growth.

• Fossil fuels are limited.

Question 51. Write two different ways of harnessing energy from the ocean.
Answer: The two different ways of harnessing energy from the ocean are as follows:

1. Tidal energy—the energy derived from rising and falling ocean tides is called tidal energy.
2. Ocean thermal energy—solar energy stored in the oceans in heat is known
   as ocean thermal energy.

Question 52. What steps would you suggest to minimise environmental pollution caused by the burning of fossil fuels?
Answer:

1. Use of smokeless appliances
2. Afforestation

Question 53. What is the role of the plane mirror and a glass sheet in a solar cooker?
Answer: A plane mirror acts as a reflector and a glass sheet results in a greenhouse effect.

Question 54. Mention three advantages of solar cells.
Answer: Solar cells have no moving parts.

1. Requires little maintenance.
2. They can be set up in the remote areas.

Question 55. What is biomass? What can be done to obtain bio-energy using biomass?
Answer: The waste material of living things and dead parts of plants and animals is called biomass.

1. It has been a traditional source of energy, e.g. wood, crop residue, and bagasse cow-dung cake are used as fuels for domestic as well as industrial uses.
2. Bio-energy in the form of biogas can be produced from biomass by the decomposition in the absence of air. Biomass such as wood, cow dung etc., is directly used as fuel.

Question 56. What are the limitations of obtaining energy from wind?
Answer: Because wind energy is erratic energy cannot be harnessed continuously.

Large areas are required for wind forms.

Question 57. Suggest any three ways to contribute to saving LPG/CNG at home.
Answer: Soak dais, and rice in water before cooking, so that it takes less time and fuel for cooking.

1. Use a pressure cooker most of the time.
2. Cover the lid of the container while cooking.

Question 58. A student constructed a box-type solar cooker. He found that it was not working efficiently. What could this be due to? Give any four possible mistakes in the construction and operation of the solar cooker. What maximum temperature can ordinarily be reached inside a solar cooker?
Answer: He might not have painted the box black from the inside.

1. He might not have placed the blackened sheet in the insulated part of the solar cooker.
2. He might not have attached the reflector at the right angle.
3. He might not have covered his box with a thick glass sheet. He might have used a thin glass sheet.

Question 59. A student wants to design a car which runs on any alternative source ofenergy. Suggest any two sources ofenergy and give their advantages.
Answer: Solar cell panels can be installed on the top of the roof. It can convert solar energy into electrical energy.

Use water as a fuel which can split into H2 and 02 gas. H2 gas produced is used to run the engine.

Question 60. A person ‘A’ rolled up the glasses of his black car and parked it in the sun for one hour. Another person ‘B’rolled up the glasses of a white car and parked in the sun for one hour. In which car is the temperature higher and why?
Answer: Black car; the black colour is a good absorber ofheat and glass causes the greenhouse effect.

Question 61. The waste materials collected from a market complex are scrap paper, thermocol, vegetable waste, tin cans and glass bottles. Which ofthese can be used for producing biogas? Mention three advantages of converting these into biogas rather than burning them.
Answer: Scrap paper and vegetables can be used to produce biogas. Converting these into biogas has the following advantages:

1. It produces cheap and valuable fuel for which there is a great demand.
2. It utilizes those substances which would, otherwise be wasted and, require space for their safe dumping.
3. If this waste is left as such then it will be decomposed by microorganisms. This results in the release of harmful gases which increases environmental pollution.

Question 62. “A biogas plant solves the fuel as well as environmental problems”. Discuss.
Answer: Biogas is an ideal fuel, as:

1. It has a high calorific value.
2. It does not produce smoke.
3. It has a moderate ignition temperature.
4. It does not form harmful products.
5. It is very cheap and can be made available easily.

Because of the above-mentioned characteristics:

1. Biogas acts as an excellent fuel and hence solves the fuel problem.
2. Biogas does not create air pollution, therefore, it solves environmental problems also.
3. Biogas also prevents water pollution.

Sources Of Energy Multiple Choice Questions

Question 1. Which of the following is a non-renewable source of energy?

1. Wood
2. Sun
3. Fossil fuels
4. Wind

Answer: 3. Fossil fuels

Question 2. Acid, rain happens because.

1. Sun leads to the heating of the upper layer of the atmosphere
2. Burning of fossil fuels releases oxides of carbon, nitrogen and sulphur in the atmosphere
3. Electrical charges are produced due to friction among clouds
4. Earth’s atmosphere contains acids

Answer: 2. Burning of fossil fuels releases oxides of carbon, nitrogen and sulphur in the atmosphere

Question 3. Fuel used in thermal power plants is

1. Water
2. Uranium
3. Biomass
4. Fossil fuels

Answer: 4. Fossil fuels

Question 4. In a hydropower plant

1. Potential energy possessed by stored water is converted into electricity
2. Kinetic energy possessed by stored water is converted into potential energy
3. Electricity is extracted from water
4. Water is converted into steam to produce electricity

Answer: 1. Potential energy possessed by stored water is converted into electricity

Question 5. Which is the ultimate source of energy?

1. Water
2. Sun
3. Uranium
4. Fossil fuels

Answer: 2. Sun

Question 6. Which one of the following forms of energy leads to the least environmental pollution in the process of harnessing and utilisation?

1. Nuclear energy
2. Thermal energy
3. Solar energy
4. Geothermal energy

Answer: 3. Solar energy

Question 7. Ocean thermal energy is due to

1. Energy Stored By Waves In The Ocean
2. Temperature Difference At Different Levels In The Ocean
3. Pressure Difference At Different Levels In The Ocean
4. Tides Arising Out In The Ocean

Answer: 2. Temperature Difference At Different Levels In The Ocean

Question 8. The major problem in harnessing nuclear energy is how to

1. Split Nuclei?
2. Sustain The Reaction?
3. Dispose Of Spent Fuel Safely?
4. Convert Nuclear Energy Into Electrical Energy?

Answer: 3. Convert Nuclear Energy Into Electrical Energy?

Question 9. Which part of the solar cooker is responsible for the greenhouse effect?

1. Coating with black colour inside the box
2. Mirror
3. Glass sheet
4. The outer cover of the solar cooker

Answer: 3. Outer cover of the solar cooker

Question 10. The main constituent of biogas is

1. Methane
2. Carbon Dioxide
3. Hydrogen
4. Hydrogen Sulphide

Answer: 1. Methane

Question 11. The power generated in a windmill is greater in the rainy season since damp air would mean more air mass hitting the blades

1. Depends On The Height Of The Tower
2. Depends On Wind Velocity
3. Can Be Increased By Planting Tall Trees Close To The Tower

Answer: 3. Can Be Increased By Planting Tall Trees Close To The Tower

Question 12. Choose the correct statement

1. Sun can be taken as an inexhaustible source of energy
2. There is infinite storage of fossil fuel inside the earth
3. Hydro and wind energy plants are non-polluting sources of energy
4. Waste from a nuclear power plant can be easily disposed off

Answer: 1. The Sun can be taken as an inexhaustible source of energy

Question 13. In a hydroelectric power plant, more electrical power can be generated if water falls from a greater height because

1. Its Temperature Increases
2. Larger Amount Of Potential Energy Is Converted Into Kinetic Energy
3. The Electricity Content Of Water Increases With Height
4. More Water Molecules Dissociate Into Ions

Answer: 2. Larger Amount Of Potential Energy Is Converted Into Kinetic Energy

Question 14. Choose the incorrect statement regarding wind power

1. It is expected to harness wind power to a minimum in open space
2. The potential energy content of wind blowing at high altitudes is the source of wind power
3. Wind hitting the blades of a windmill causes them to rotate. The rotation thus achieved can be utilised further
4. One possible method of utilising the energy of the rotational motion of the blades of a windmill is to run the turbine of an electric generator.

Answer: 2. The potential energy content of wind blowing at high altitudes is the source of wind power

Question 15. Choose the incorrect statement

1. We are encouraged to plant more trees to ensure a clean environment and also provide biomass fuel
2. Gobar gas is produced when crops, vegetable wastes etc., decompose in the absence of oxygen
3. The main ingredient of biogas is ethane and it gives a lot of smoke and also produces a lot of residual ash
4. Biomass is a renewable source of energy

Answer: 3. The main ingredient of biogas is ethane and it gives a lot of smoke and also produces a lot of residual ash.

Question 16. A solar water heater cannot be used to get hot water on

1. A Sunny Day.
2. A Hot Day.
3. A Cloudy Day.
4. A Windy Day.

Answer: 2. A cloudy day (because on a cloudy day, no radiations from the sun are incidentÿn the solar water heater. Hence, it cannot be used to get hot water).

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

1. Wood
2. Gobar-Gas
3. Nuclear Energy
4. Coal.

Answer: 3. Nuclear energy.

Question 18. Most ofthe sources of energy we use represent stored solar energy. Which ofthe following is not ultimately derived from the Sun’s energy?

1. Geothermal energy
2. Nuclear energy
3. Wind energy
4. Biomass

Answer: 1. Geothermal energy.