NCERT Exemplar Solutions Class 10 Science Sources of Energy

Read NCERT Exemplar Solutions Class 10 Science Sources of Energy below, students should study NCERT Exemplar class 10 Science available on Studiestoday.com with solved questions and answers. These chapter wise answers for class 10 Science Exemplar problems have been prepared by teacher of Grade 10. These NCERT Exemplar class 10 Science solutions have been designed as per the latest NCERT syllabus for class 10 and if practiced thoroughly can help you to score good marks in standard 10 Science class tests and examinations

Multiple Choice Questions.........................


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

(a) Wood

(b) Sun

(c) Fossil fuels

(d) Wind 

Solution 1: (b) Sun 

Sun is a non-renewable source of energy.

 

Question 2: Acid rain happens because

(a) sun leads to heating of the upper layer of the atmosphere

(b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere

(c) electrical charges are produced due to friction amongst clouds

(d) earth atmosphere contains acids 

Solution 2:  (b) burning of fossil fuels release oxides of carbon, nitrogen and sulphur in the atmosphere

Acid rain occurs as rainwater reacts with carbon, nitrogen, and sulphur oxides in the atmosphere.

 

Question 3:  Fuel used in thermal power plants is

(a) water

(b) uranium

(c) biomass

(d) fossil fuels 

Solution 3:  (d) fossil fuels

The most common fossil fuel used in thermal power plants is coal. Natural gas and petroleum are also used in addition to coal.

 

Question 4:  In a hydropower plant

(a) Potential energy possessed by stored water is converted into electricity

(b) Kinetic energy possessed by stored water is converted into potential energy

(c) Electricity is extracted from water

(d) Water is converted into steam to produce electricity 

Solution 4: (a) Potential energy possessed by stored water is converted into electricity.

Dam water has the capacity to store electricity. It has potential energy when released, which is used to transform the turbines. Turbines are machines that generate electricity.

 

Question 5: Which is the ultimate source of energy?

(a) Water

(b) Sun

(c) Uranium

(d) Fossil fuels 

Solution 5: (b) Sun 

Solar energy is used by plants to grow food. Fossil fuels are made from decomposing plants. As a result, Sunlight is the direct or indirect source of all electricity.

 

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

(a) Nuclear energy

(b) Thermal energy

(c) Solar energy

(d) Geothermal energy 

Solution 6: (c) Solar energy 

Metals such as uranium are used in nuclear energy, which emit radioactive rays that can damage living organisms. Coal is used in thermal energy, which releases sulphur and carbon dioxide into the atmosphere, causing emissions. In geothermal energy, the energy is consumed by the weight of the core's heat, which can be incredibly hot and hazardous at times.

 

Question 7:  Ocean thermal energy is due to

(a) energy stored by waves in the ocean

(b) temperature difference at different levels in the ocean

(c) pressure difference at different levels in the ocean

(d) tides arising out in the ocean 

Solution 7:  (b) temperature difference at different levels in the ocean

To boil a volatile liquid, energy from the surface is used. The turbine is turned by the vapours from these.

 

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

(a) split nuclei?

(b) sustain the reaction?

(c) dispose of spent fuel safely?

(d) convert nuclear energy into electrical energy? 

Solution 8: (c) dispose off spent fuel safely? 

Nuclear power plants generate highly radioactive waste. When these substances are released into the atmosphere, they pose a significant threat to living organisms. As a result, safely disposing of spent fuel is a big issue in harnessing nuclear energy.

 

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

(a) Coating with black colour inside the box

(b) Mirror

(c) Glass sheet

(d) Outer cover of the solar cooker 

Solution 9: (c) Glass sheet 

The greenhouse effect is caused by the atmosphere trapping heat. The presence of greenhouse gases such as CO2 and SO2 causes heat to be released. The same thing happens in a solar cooker. The trapped solar energy is mirrored by the glass layer, causing the food to cook.

 

Question 10:  The main constituent of biogas is

(a) methane

(b) carbon dioxide

(c) hydrogen

(d) hydrogen sulphide 

Solution 10: (a) methane 

Biogas produces primarily methane gas. Around 70% of the gas produced is methane, with the remainder being ammonia and carbon dioxide.

 

Question 11:  The power generated in a windmill

(a) is more in rainy season since damp air would mean more air mass hitting the blades

(b) depends on the height of the tower

(c) depends on wind velocity

(d) can be increased by planting tall trees close to the tower 

Solution 11:  (c) depends on wind velocity

When the wind speed is high, the turbine can spin faster. The amount of electricity generated will rise as a result of this.

 

Question 12:  Choose the correct statement

(a) Sun can be taken as an inexhaustible source of energy

(b) There is infinite storage of fossil fuel inside the earth

(c) Hydro and wind energy plants are non-polluting sources of energy

(d) Waste from a nuclear power plant can be easily disposed off 

Solution 12: (a) Sun can be taken as an inexhaustible source of energy 

Fossil fuels are a finite resource. Hydro and wind energy plants may have a significant environmental effect in the dam area by altering the climate and impacting land use, housing, and natural ecosystems. The biggest problem that a nuclear power plant faces is how to dispose of its waste.

  

Question 13:  In a hydroelectric power plant, more electrical power can be generated if waterfalls from a greater height because 

(a) its temperature increases 

(b) larger amount of potential energy is converted into kinetic energy 

(c) the electricity content of water increases with height 

(d) more water molecules dissociate into ions 

Solution 13:  (b) larger amount of potential energy is converted into kinetic energy 

More electrical power can be produced in a hydroelectric power plant if the waterfalls are higher since a larger amount of potential energy is converted into kinetic energy.  

 

Question 14:  Choose the incorrect statement regarding wind power 

(a) It is expected to harness wind power to minimum in open space 

(b) The potential energy content of wind blowing at high altitudes is the source of wind power 

(c) Wind hitting at the blades of a windmill causes them to rotate The rotation thus achieved can be utilised further 

(d) One possible method of utilising the energy of rotational motion of the blades of a windmill is to run the turbine of an electric generator  

Solution 14:  (b) The potential energy content of wind blowing at high altitudes is the source of wind power. 

The kinetic energy of the wind is used to fuel wind turbines. As a result, statement b) is incorrect. 

 

Question 15: Choose the incorrect statement 

(a) We are encouraged to plant more trees so as to ensure a clean environment and also provide bio-mass fuel 

(b) Gobar-gas is produced when crops, vegetable wastes etc., decompose in the absence of oxygen 

(c) The main ingredient of bio-gas is ethane and it gives a lot of smoke and also produces a lot of residual ash 

(d) Biomass is a renewable source of energy 

Solution 15:  (c) The main ingredient of bio-gas is ethane and it gives a lot of smoke and also produces a lot of residual ash

Methane is the primary product of a biogas system. It produces less smoke and no residual ash when burned.

 

Short Answer Questions..........................


Question 16:  Why is there a need to harness non-conventional sources of energy? Give two main reasons. 

Solution 16:   The reasons for the need to harness non-conventional energy sources are as follows.

(i) Non-conventional energy sources did not pollute the atmosphere.

(ii) Conventional energy sources are finite and will be depleted in the not-too-distant future.

 

Question 17:  Write two different ways of harnessing energy from the ocean. 

Solution 17:   Two different ways of harnessing energy from the ocean are as follows:

(i) Tidal energy

(ii) Ocean Thermal energy

 

Question 18:  What steps would you suggest to minimise environmental pollution caused by the burning of fossil fuels? 

Solution 18:   The following are steps to reduce emissions caused by the burning of fossil fuels:

(i) To reduce air pollution, afforestation should be used.

(ii) To minimise noise, smokeless appliances should be used.

(iii) Use non-conventional energy sources including hydrothermal and wind power.

 

Question 19:  What is the role of a plane mirror and a glass sheet in a solar cooker? 

Solution 19:   The sun is reflected by a plane mirror, which increases the strength of solar radiation. The solar cooker's heat is held in by a glass sheet.

 

Question 20:  Mention three advantages of a solar cell? 

Solution 20:   The following are some of the benefits of a solar cell.

• Solar cells are a clean energy source.

• Solar cells require minimal maintenance.

• Solar cells do not pollute the environment.

 

Question 21:  What is biomass? What can be done to obtain bio-energy using biomass? 

Solution 21:   Biomass is a type of fuel made from organic materials. The methods for obtaining bio-energy from biomass are described below:

  • Gobar gas can be manufactured.
  • Making a cow dung cake and using it as a heat source.
  • Gobar can be used to generate electricity.
  • Using firewood as a source of energy.

 

Question 22: What are the limitations in obtaining energy from wind? 

Solution 22:  Wind energy has its own set of limitations:

  • The wind should have a minimum speed of 15 km/h.
  • There will be no clear and continuous output.
  • The installation of a wind power mill necessitates a significant amount of space.


Long Answer Questions............................


Question 23:  Which is the process used to harness nuclear energy these days? Explain it briefly. 

Solution 23:   Nuclear power plants use nuclear energy to generate electricity. It is equipped with a nuclear reactor, a boiler, and a turbine.

• To generate electricity, steam is used to transform turbines.

• A nuclear reactor is a device that uses nuclear fission to produce energy. Nuclear fission generates enormous amounts of steam.

• The heat created by nuclear fission is used to boil water in order to create steam.

 NCERT Exemplar Solutions Class 10 Science Sources of Energy

Question 24: How can solar energy be harnessed? Mention any two limitations in using solar energy. How are these limitations overcome? 

Solution 24:

Solar Cooker:

Under similar conditions, a black surface absorbs more heat than a white or reflecting surface. This property is used in the use of solar cookers and solar water heaters. Some solar cookers use mirrors to concentrate the Sun's rays, resulting in a higher temperature. A glass plate is used to cover solar cookers. The trapped solar energy is mirrored by the glass layer, making the food cooked. 

Solar Cell:

When exposed to the Sun, a typical cell develops a voltage of 0.5–1 V and can produce about 0.7 W of electricity. A solar cell panel is an array of a large number of solar cells that can produce enough energy for practical use.

Solar cells have a number of benefits, including the fact that they have no moving parts, need minimal maintenance, and operate well without the use of a focussing system. Another benefit is that they can be installed in remote and inaccessible hamlets or sparsely populated areas where laying a power transmission line would be prohibitively costly and unprofitable.

 

Question 25:  Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one nonconventional source of energy. 

Solution 25:   Coal, petroleum, firewood, and tidal energy are all traditional energy sources.

Solar energy, nuclear energy, biogas, tidal energy, ocean thermal energy, and wave energy are examples of non-conventional energy sources.

Methods for using non-conventional energy sources:

Solar cookers, solar water heaters, solar cells, and solar panels can all be used to harvest solar energy.

Nuclear reactors are used to turn nuclear energy into electric energy.

The Sun heats the water at the sea's or ocean's level, but the water in deeper parts is relatively cold. This temperature difference is used to generate electricity in ocean-thermal-energy conversion plants.

Large waves along the seashore have kinetic energy that can be trapped in a similar way to produce electricity. Strong winds flowing through the sea cause the waves to form. Only where there are very powerful waves would wave energy be a viable option.

 

Question 26:  Why is there a need for harnessing non-conventional sources of energy? How can energy be harnessed from the sea in different ways? 

Solution 26:   The reasons for the need to harness non-conventional energy sources are as follows:

(i)      Conventional energy sources are finite and will be depleted in the not-too-distant future.

(ii)    Non-conventional energy sources did not pollute the atmosphere. 

The following methods can be used to extract energy from the sea:

Tidal energy:

Construction of a dam over a narrow opening to the sea is used to harness tidal energy. Tidal energy is converted to electricity by a turbine located at the dam's opening. As you would expect, the number of places where such dams can be constructed is small.

Wave energy:

Large waves along the seashore have kinetic energy that can be trapped in a similar way to produce electricity. Strong winds flowing through the sea cause the waves to form. Only where there are very powerful waves would wave energy be a viable option.

Ocean Thermal Energy:

The Sun heats the water at the sea's or ocean's level, but the water in deeper parts is relatively cold. This temperature difference is used to generate electricity in ocean-thermal-energy conversion plants.

 

Question 27:  What are the environmental consequences of using fossil fuels? Suggest the steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy. 

Solution 27:   The following are the ramifications of burning fossil fuels:

• Increased carbon dioxide levels cause global warming.

• Sulphur oxides cause acid rain.

• Burning fossil fuels causes smog to build up in major cities, reducing visibility.

• Air pollution poses health risks to humans and animals. 

Steps to reduce pollution caused by various energy sources, including non-conventional energy sources: 

  • Afforestation: It is the establishment of a forest or stand of trees in an area where there was no previous tree cover.
  • Taking public transportation.
  • Adopting the 3R's policy: reduce, reuse, and recycle.
  • Using cars that can mitigate air emissions, such as hybrid bikes and bicycles.

 

Question 28:  Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer. 

Solution 28:   The sun is thought to have provided energy to a variety of sources. The following points can be used to back up the argument.

Because of this, energy from fossil fuels is partially harnessed from sunlight. Plants capture sunlight to produce food, which is then converted into biomass. Biomass is burned to produce fossil fuels. 

  • Biomass would aid in the acquisition of wood and gobar gas.
  • The sun's kinetic energy causes the earth's water to circulate.
  • Water heating causes waves and the ocean to shape. As a result, the sun is indirectly responsible for tidal, wave, and geothermal energy harvesting.

 

Question 29:  What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram. 

Solution 29:   Biomass refers to fuel sources derived from organic matter.

In the absence of oxygen, cow dung, various plant materials such as crop residue, vegetable waste, and sewage decompose to produce bio-gas.

The plant is constructed in the shape of a dome and is made of bricks. In the mixing tank, slurry of cow dung and water is produced, which is then fed into the digester. The digester is a vacuum-sealed chamber with no oxygen. The cow-dung slurry is decomposed or broken down by anaerobic microorganisms that do not require oxygen. The decomposition process takes a few days to complete and produces gases such as methane, carbon dioxide, hydrogen, and hydrogen sulphide. The bio-gas is contained in a tank above the digester, from which it is drawn for use through pipes. 

 NCERT Exemplar Solutions Class 10 Science Sources of Energy 

Biogas is a great fuel because it contains up to 75% methane. It doesn't produce smoke and doesn't produce ash as wood, charcoal, or coal do. It has a large heating range. Lighting is also powered by biogas. The slurry that remains is removed on a regular basis and used as a high-nitrogen, high-phosphorous manure. The large-scale use of bio-waste and sewage material not only provides energy and fertiliser, but it also provides a healthy and effective form of waste disposal.

Chapter 16 Sustainable Management of Natural Resources
NCERT Exemplar Solutions Class 10 Science Management of Natural Resources