CBSE Class 10 Science Sources Of Energy Worksheet

Read and download free pdf of CBSE Class 10 Science Sources Of Energy Worksheet. Students and teachers of Class 10 Science can get free printable Worksheets for Class 10 Science Chapter 14 Sources of Energy in PDF format prepared as per the latest syllabus and examination pattern in your schools. Class 10 students should practice questions and answers given here for Science in Class 10 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 10 Science Worksheets prepared by teachers as per the latest Science books and syllabus issued this academic year and solve important problems with solutions on daily basis to get more score in school exams and tests

Worksheet for Class 10 Science Chapter 14 Sources of Energy

Class 10 Science students should refer to the following printable worksheet in Pdf for Chapter 14 Sources of Energy in Class 10. This test paper with questions and answers for Class 10 will be very useful for exams and help you to score good marks

Class 10 Science Worksheet for Chapter 14 Sources of Energy

SOURCE OF ENERGY

Thermal power plants
• Thermal power plants use steam produced by burning fossil fuels (mainly coal) to move the turbines to generate electricity.
• The burning of coal heats up the water and forms steam that is used to run the turbine.
• Usually, Thermal power plants are located near coal or oil fields as it is easier to transmit electricity than transport coal.

Hydropower Plants
Turbines
• A turbine is a rotatory mechanical device that extracts kinetic energy in various forms and converts it into useful work. It uses a dynamo to convert this mechanical energy into electrical energy.
• Various uses of this have been implemented in power plants where the shaft of the dynamo is made to rotate by mechanical means.

Hydropower plants
• Another traditional source of energy is from the kinetic energy of flowing water or harnessing potential energy of water falling from a height.
• The falling/flowing water moves the turbine, which with the help of a dynamo converts mechanical energy into electrical energy.
• Hydropower plants are usually constructed near dams or waterfalls.
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Dams A dam is a barrier that impounds water or underground streams. The water is ejected upon requirement by the power plant to generate hydroelectricity.

Fuels
Biomass
• Biomass is the source of energy derived from living things (organic matter). For a long time, we relied on wood for the source of heat energy. In India, we make fuel out of biowaste such as cow dung due to the availability of a thriving population of livestock.
• When wood is burnt in a limited supply of oxygen and water until volatile materials are removed, the residue left behind is charcoal. Charcoal has good heat generating efficiency. It also burns without flames.
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Bio-gas plant
• In India cow dung, sewage waste, plant matter are decomposed in absence of oxygen to produce biogas. Since it has cow dung it is often termed as gobar gas
• A biogas plant is a dome-like structure built with bricks where cow dung and other biowaste are mixed with water to form a slurry and put into a digester.
• The digester is a sealed chamber with anaerobic bacteria which breaks down the slurry.
• This decomposition process releases gases like methane, CO2, hydrogen sulfide and hydrogen.
• These gases are drawn via pipes which are transmitted to a turbine for the production of electricity.

Wind Energy

Wind energy

• Environment-friendly efficient source of energy.
• Wind is the natural phenomenon caused by pressure differentials due to unequal heating of land and water masses on the surface of the earth. It is harnessed in the form of kinetic energy.

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Windmill
• Wind Energy is harnessed by rotatory structures known as windmills.
• They have huge blades or fans attached very high on a rigid support that is attached to turbines that rotate due to high speeds of wind and generate electricity.
• A single windmill has a low output and therefore, the wind farms are built that comprises of several windmills.

Advantages and limitations of wind energy Advantages: Environment-friendly, efficient, renewable source, with no recurring cost for production of electricity.

Limitations:
• Wind speeds should be constant and > 15 km/h.
• Must have back up storage facilities like cells.
• Requires large land area.
• High initial cost and regular maintenance are required

QUESTIONS BASED ON ABOVE TOPICS:-

Question : The thermal efficiency of a steam power station is….......
Answer : 28%

Question : The height of chimney in a staem power plant is governed by........
Answer : The draught to be produced

Question : What is the source of energy in hydro power plants?
Answer : Flowing water

Question : Explain in brief about the process of formation of electricity from hydro power plants.
Answer : Hydro Power Plants convert kinetic energy of flowing water or potential energy of water at a height into mechanical energy and mechanical energy so produced in converted into electrical energy. Electricity produced from Hydro Power Plants, big and high rise dams are constructed on the river.

Question : What are 5 advantages of hydropower?
Answer : Advantages of Hydroelectric Energy
• 1 Renewable. Hydroelectric energy is renewable. ...
• 2 Green. Generating electricity with hydro energy is not polluting itself. ...
• 3 Reliable. Hydroelectricity is very reliable energy. ...
• 4 Flexible. As previously mentioned, adjusting water flow and output of electricity is easy. ...
• 5 Safe.

Question : Is biogas cheaper than LPG?
Answer : CNG car cylinder shown above can be easily swapped with Biogas (gobar gas) because both are the same thing - METHANE. Biogas is more safer than CNG and 3 times more safer than LPG cylinder. Biogas is the Cheapest and never ending multipurpose fuel.

Question : Is biogas a fossil fuel?
Answer : Biogas is also a hydrocarbon fuel, but generally speaking biogas is not a fossil fuel because it was not mined and captured from a geological deposit. Even if biogas is purified to be almost identical to natural gas it is still not a fossil fuel, but rather renewable methane.

Question : What are the limitations of wind energy ?
Answer : (i) Wind energy farms can be set only at places where wind blows for a greater part of the year.
• (ii) Wind speed should be greater than 15 km/h.
• (iii) Require vast area of land to set up wind farm.
• (iv) Initial cost of establishment of wind farm is very high.

Question : How you can produce electricity from a wind farm?
Answer :

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Question : If energy can neither be created nor destroyed, explain with an example as to why we should worry about our energy crisis?
Answer : Energy comes in different forms and one form can be converted into another form. For example-if we light a candle, the process is highly exothermic so that the chemical energy in the candle changes into heat energy and light energy on burning. The total energy during a physical and chemical process remains the same but we cannot again put together the heat and light generated along with the products of the reaction to get back the chemical energy in the form of wax. Hence, energy, in the usable form, is dissipated to the surroundings in less usable forms. So the sources of energy we use to do work is consumed and cannot be used again.

Very Short Answers

Question : Name any two conventional sources of energy.

Answer : Petroleum and Coal are the two conventional sources of energy.

Question : Mention the purpose of blackening the interior of a solar cooker.

Answer : In a solar cooker, the inside area is painted black because black colour absorbs sun rays and does not reflect back which helps in increasing the inside temperature of the solar cooker rapidly.

Question : Why does acid rain happen?

Answer : Acid rain happens because of burning of fossil fuels which release oxides of carbon, nitrogen and sulphur in the atmosphere. These oxides of carbon, nitrogen and sulphur when get mixed up with water form acids like carbonic acid, nitric acid and sulphuric acid which results in the form of acid rains..

Question : Name two combustible components of biogas.

Answer : Methane (CH₄) and Hydrogen (H₂) are two combustible components of biogas.

Short Answers

Question : A student constructed a box type solar cooker. He found that it did not work 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 have done the following mistakes.

i. Interior of the solar cooker is not painted with black colour.

ii. Instead of glass sheet, plastic sheet is used to cover it.

iii. Solar cooker is without insulation.

iv. Black containers have not been used.

Maximum temperature that can be obtained inside a solar cooker is 140^oC.

Question : Expand OTEC. On what principle is it based?

Answer : OTEC: Ocean Thermal Energy Conversion.

OTEC is based on the temperature gradient between upper and lower layers of the ocean.

There is a difference of 20^oC between the upper and lower levels. This is exploited to form energy.

Question : Hydrogen compounds are abundantly available on earth and they have a high calorific value but this gas is not commonly used as a domestic fuel. Give any two reasons for this.

Answer : Hydrogen is not used as a domestic fuel because of following reasons :

i. Hydrogen is highly combustible and is difficult to handle safely. Because of its high combustible nature, it burns with explosion.

ii. It is not easy to store or transport hydrogen from one place to another safely.

Question : Name the type of reaction in the sun which produces its energy. List two conditions which are present at the center of sun responsible for this reaction.

Answer : The nuclear reactions which take place in the sun are the nuclear fusion reactions.

Conditions for the following reaction are:

1. In these reactions, two small nuclei fuse together to form a bigger nucleus, with evolution of large amount of energy (almost three to four times greater than nuclear fission reaction).

2. These reactions require very high temperatures.

Long Answers

Question : Compare biomass and biogas.

Answer : Comparison between Biomass and Biogas as fuel.

Biomass (Wood/Cow dung cakes)

i. It produces too much smoke.

ii. Its calorific value is very low.

iii. Ash is left as residue.

iv. Organic manure gets burnt when cow dung cakes are burnt.

v. Using wood as a fuel requires cutting of tree. Deforestation leads to many problems. Again cow dung cakes burn organic manure. Hence less manure is available to make land fertile.

Biogas

i. It does not produce any smoke.

ii. Its calorific value is very high.

iii. It does not leave any ash.

iv. Organic matter gets enriched as spend slurry.

v. Biogas uses waste biomass. It makes environment neat and clean.

Question : What are hazards of incomplete combustion ?

Answer : Hazards of Incomplete combustion :

Fuels contain a good amount of carbon. When combustion is complete, most of carbon gets converted into harmless carbon dioxide but when combustion is incomplete, the carbon does not burn properly resulting in following hazards :

a. Major portion of carbon gets converted into extremely poisonous carbon monoxide. Carbon monoxide pollutes the atmosphere and causes acute respiratory problems.

b. Sun emits a very large amount of ultraviolet rays which are very harmful to us.

These radiations are stopped by layer of ozone gas (O₃) present between 50 to 80 km from earth. thus we are saved from harmful effect of ultraviolet rays. Carbon monoxide produced due to partially burnt carbon combines with ozone and gets converted to carbon dioxide.

CO + O₃ →CO₂ + O₂

This damages ozone layer and hence exposes us to harmful of ultraviolet radiations. If the automobiles are not properly services and tuned, they produce a large amount of partially burnt carbon monoxide. This is the reason as to why the government stresses for periodical pollution tests.

c. During partial combustion some of the unburnt carbon passages into atmosphere in form of soot. There is not only sheer wastage of fuel but also pollutes atmosphere.

Question. Gasoline is produced by refining which fossil fuel?
(a) natural gas
(b) coal
(c) petroleum
(d) propane
Answer : C

Question. Acid rain happens because
(a) sun leads to heating of upper layer of 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
Answer : B

Question. 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
Answer : B

Question. The main constituent of bio-gas is
(a) methane
(b) carbon dioxide
(c) hydrogen
(d) hydrogen sulphide
Answer : A

Question. 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 Choose the correct statement
Answer : C

Question. Most of the energy we use originally came from
(a) the sun
(b) the air
(c) the soil
(d) the oceans
Answer : A

Question. Natural gas is transported mainly by
(a) pipelines
(b) trucks
(c) barges
(d) al three equally
Answer : A

Question. Propane is used instead of natural gas on many farms and in rural areas. Why is propane often used instead of natural gas?
(a) it’s safer
(b) it’s portable
(c) it’s cleaner
(d) it’s cheaper
Answer : B

Question. While filling LPG in cylinders, a substance X is added to make the detection of leakage of LPG from the cylinder easy. The substance X is
(a) ethanol
(b) ethanethiol
(c) methanethiol
(d) methanol
Answer : B

Question. Coal, petroleum, natural gas, and propane are fossil fuels. They are called fossil fuels because:
(a) they are burned to release energy and they cause air pollution
(b) they were formed from the buried remains of plants and tiny animals that lived hundred of millions of years ago
(c) they are non-renewable and will run out
(d) they are mixed with fossils to provide energy
Answer : B

Question. Which environmental hazard is not contributed by the combustion of fossil fuels?
(a) Acid rain
(b) Greenhouse effect
(c) Destruction of wildlife habitat
(d) Air pollution
Answer : C

Question. Which part of the solar cooker is responsible for green house effect?
(a) Coating with black colour inside the box
(b) Mirror
(c) Glass sheet
(d) Outer cover of the solar cooker
Answer : C

Question. When the material P mined from the earth is heated strongly in an insufficient supply of air, it produces a solid fuel Q which mainly consist of carbon. When another material R obtained from trees is heated in an insufficient supply of air, it produces another solid fuel S which also consists mainly of carbon. Then, which of the following is true?
(a) P-coke
(b) Q-coal
(c) R-charcoal
(d) None of these
Answer : D

Question. Electrical energy can be produced from
(a) mechanical energy
(b) chemical energy
(c) radiant energy
(d) All of the above
Answer : D

Question. In a hydro-power 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.
Answer : A

Question. The mass number of four different elements A,B,C and D are 2, 35, 135 and 239, respectively. Which of them would provide the most suitable for nuclear fission?
(a) A
(b) C
(c) C
(d) D
Answer : A

Question. 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
Answer : A

Question. Which of the following is non-conventional source of energy

A. Solar energy

B. Hydro energy

C. OTE

D. Wind energy

a. A and C

b. A and D

c. A and B

d. B and C

Answer : A

Explanation: Because these sources of energy can be easily renewed with minimum effort and money, pollution free and eco friendly

Question. Which of following is more environment friendly?

a. Burning of charcoal

b. Burning of fire wood

c. Burning of diesel

d. Burning of coal

Answer : A

Explanation: Burning of charcoal is more environmental friendly because it is fully a biofuel which has minimum pollution effect. It has least carbon emission.

Question. Match the following with correct response.

a. 1-C, 2-B, 3-D, 4-A

b. 1-B, 2-D, 3-A, 4-C

c. 1-D, 2-A, 3-C, 4-B

d. 1-A, 2-C, 3-B, 4-D

Answer : C

Explanation:

i. Biomass is made of Fossil fuels--Biomass most often refers to plants or plant-based materials that are not used for food or feed, and are specifically called lignocellulosic biomass. As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel

ii. Chain reaction in atom bomb is Uncontrolled-A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions to take place. In a chain reaction, positive feedback leads to a self-amplifying chain of events.

iii. Fuel used in nuclear power plant is U-235--Nuclear power plants do not burn any fuel. Instead, they use uranium fuel, consisting of solid ceramic pellets, to produce electricity through a process called fission.

Watch our interactive graphic on how nuclear fuel is produced, used and stored.

iv. Process by which energy is produced in the sun Nuclear fusion--

The Sun is about halfway through its main-sequence stage, during which nuclear fusion reactions in its core fuse hydrogen into helium. Each second, more than four million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation.

Question. Match the following with correct response.

a. 1-B, 2-D, 3-A, 4-C

b. 1-D, 2-A, 3-C, 4-B

c. 1-C, 2-B, 3-D, 4-A

d. 1-A, 2-C, 3-B, 4-D

Answer : A

Explanation:

i. The group of solar cells joined together in definite pattern is solar panel---Solar panels are those devices which are used to absorb the sun's rays and convert them into electricity or heat. Description: A solar panel is actually a collection of solar (or photovoltaic) cells, which can be used to generate electricity through photovoltaic effect

ii. The device used for obtaining energy for flowing water is water wheel----A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill

iii. A barrier constructed on the river to store the flowing water is dam---A dam is usually constructedacross a river to create a reservoir in the valley behind by storing the water that flows into it naturally. ... Small rivers and streams are usually diverted through a tunnel, or a channel that is constructed around the side of the dam

iv. A domestic fuel which contains butane is LPG---Liquefied petroleum gas or liquid petroleum gas (LPG or LP gas), also referred to as simply propane or butane, are flammable mixtures of hydrocarbon gases

Question. What is present contribution of hydro electric power stations to the electricity generated in India?

a. 20%

b. 23%

c. 41%

d. 33%

Answer : B

Explanation: About 65% of the electricity consumed in India is generated by thermal power plants, 23% by hydroelectric power plants, 3% by nuclear power plants and rest by 10% from other alternate sources like solar, wind, biomass etc. 53.7% of India's commercial energy demand is met through the country's vast coal reserves.

Fill In The Blank

Question. A solar cell is a device which converts solar energy directly into ..........
Answer : Electricity

Question. Electricity generated from sea waves is ..........
Answer : Tidal energy

Question. ......... and .......... countries have number of power plants based on geothermal energy.
Answer : New Zealand, United States of America

Question. The internal heat of an earth is known as .......... energy.
Answer : Geothermal

Question. The energy possesses by wind is called ..........
Answer : Wind energy

Question. Coal, petroleum and .......... are the three important source of modern fuels.
Answer : Natural gas

Question. Ocean Thermal Energy plants can operate if the temperature difference between the water at the surface and water at depths up to ......... km is .......... or more.
Answer : 2, 293 k (or 20°C)

Question. Bio-gas contains .......... % methane.
Answer : 75

Question. The material obtained from the bodies of plants and animals is called ..........
Answer : Biomass

Question. Many of the sources ultimately derive their energy from the ..........
Answer : Sun

Question. When a complex material is heated strongly in the absence of air, then id decomposes to the simplest substance. This process is called ..........
Answer : Destructive distillation.

True/False

Question. The low kinetic energy (slow moving) neutrons which can produce nuclear fission are called thermal neutrons.
Answer : True

Question. Natural gas is renewable source of energy.
Answer : False

Question. Black colour is a very good absorber of heat and good reflector.
Answer : False

Question. Solar cookers make use of solar energy.
Answer : True

Question. Biogas is produced by the aerobic degradation of animal wastes like cow-dung in the presence of water.
Answer : True

Question. The sun is the ultimate source of energy.
Answer : True

Question. Deep drilling in the earth to obtain geothermal energy is very difficult.
Answer : True

Question. Sun is the source of heat contained in geothermal energy.
Answer : False

Question. The calorific value of methane is less than that or butane.
Answer : False

Question. Gobar gas is a non-renewable source of energy.
Answer : False

Assertion and Reason

DIRECTION : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.

Question. Assertion : Certain gases like carbon-dioxide, water vapour, methane are called greenhouse gases.
Reason : These gases are responsible for heating up of the atmosphere.
Answer : A

Question. Assertion : Burning of coal or petroleum products lead to air pollution.
Reason : Coal and petroleum are non renewable source of energy.
Answer : B

Question. Assertion : In street light circuits, photo-cells are used to switch on and off the lights automatically at dusk and dawn.
Reason : A photocell can convert a change in intensity of illumination into a change in photo-current that can be used to control lighting system.
Answer : A

Question. Assertion : Charcoal is a better fuel then wood for domestic purposes.
Reason : Charcoal burns without flames and does not produce smoke during burning.
Answer : A

Question. Assertion : Nuclear fusion is used to generate electricity.
Reason : Nuclear power is used because it cannot be controlled.
Answer : C

Question. Assertion : Bio-gas is a boon to the farmers.
Reason : Spent slurry is used as manure and can be used to generate electricity.
Answer : A

Very Short Answer Type Questions

Question. Why is a car parked in the sun with windows closed found to be hotter inside than outside?

Answer : Glass traps heat inside the car due to the greenhouse effect. That’s why it is hotter inside the car with a closed window than outside.

Question. Name the kind of energy possessed by wind and the device used to harness it.

Answer : The wind posses wind energy which is harnessed by using windmill.

Question. Explain, how does burning of fossil fusels cause water pollution?

Answer : Fossil fuels on burning releases harmful gases like SO₂, NO₂, etc which remain in the atmosphere and when rain occurs these gases react with rainwater to form acid rain which fall in the water bodies and cause water pollution.

Question. What energy transformations occur in a hydro power plant?

Answer : In a hydro power plant, potential energy possessed by stored water is converted into electrical energy.

Question. Name the kind of energy possessed by wind and the device used to harness it.
Answer : Kinetic energy, wind mill.

Question. What is acid rain?
Answer : Acid rain: The rain containing the acidic oxides such as oxides of carbon, nitrogen and sulphur.

Question. Define fuel. List any two characteristics that you would look for in a good fuel.
Answer : A substance that produces useful energy when it burn or undergoes a chemical for nuclear reaction. The fuel such as coal, wood, oil, or gas provides energy when burned. A good fuel is the one which produces a huge amount of heat on burning. It does not produce a lot of smoke and is easily available.

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

Question. Name the part of a biogas plant where reactions take place in the absence of oxygen.
Answer : Digester chamber.

Question. Why a solar cooker painted black form outside?
Answer : Black surface absorbs more heat as compared to white or reflecting surface under identical conditions.

Question. List two non-conventional sources of energy.
Answer : Geothermal, solar, biomass, water, wind are the non-conventional sources of energy, (any two)

Question. Write the name of the substance whose vapours are used to run the turbine of the generator of ocean thermal energy plant.
Answer : Ammonia.

Question. Bio gas is considered to be a boon to the farmers. Give reasons.
Answer : 1. It is the source of excellent manure, rich in nitrogen and phosphorous which can be obtained from the biogas plant in addition to biogas.
2. It provides the safe, efficient and profitable disposal method for bio-waste and sewage material.

Short Answer Type Questions

Question. Explain how the energy of flowing water is related to solar energy.

Answer : When solar energy falls on the water surface then evaporation of water from water surfaces like oceans, rivers and other water bodies takes place to form clouds. The clouds are then taken to distant places by air currents, and ultimately water comes back to the surface in the form of rain and snow. During evaporation, a part of solar energy gets converted into potential energy of water molecules. The potential energy of water molecules gets converted into kinetic energy during rain and snowfall. Thus, energy of water flowing in a river is considered to be an indirect form of solar energy.

Question. Define the process of nuclear fission. Write the steps involved in generating electricity in a nuclear reactor.

Answer : The process in which the heavy nucleus of a radioactive atom (such as Uranium,

Polonium or Thorium) splits up into smaller nuclei when bombarded with low energy neutrons, is called "nuclear fission".

The steps involved in generating electricity in a nuclear reactor are as follows:

i. The enriched uranium-235 rods are inserted in a core made of graphite.

ii. The Boron rods help in controlling the fission reaction by absorbing extra neutrons.

iii. The controlled fission of uranium-235 in the nuclear reactor produces a lot of heat energy.

iv. Liquid sodium or CO₂ gas is pumped continuously through the pipes embedded in the reactor. Sodium absorbs the heat energy produced in the reactor.

v. The hot sodium is then passed into the coil of heat exchanger containing water.

The water absorbs heat from hot sodium and gets converted into steam.

vi. This steam at high pressure is used to rotate the turbine. The shaft of the turbine is connected to the electric generator. When the turbine rotates, its shaft also rotates and drives the generator. The generator thus produces electricity.

Question. Give one reason as to why L.P.G. is a better fuel than kerosene oil.

Answer : Calorific value of L.P.G. is more than kerosene oil. Moreover, its ignition temperature is lower than kerosene oil and thus it starts burning even with a small spark.

Question. Why is their need to harness non-conventional sources of energy? Give two main reasons.

Answer : The reasons to harness the non-conventional source of energy are as follows:

i. The increase in population.

ii. Greater use of machines due to industrialisation.

iii. Limited supply of fossil fuels.

Question. List any three hazards of nuclear waste. How does the disposal of nuclear waste pose a problem for the plant and animal life?
Answer : Hazards of nuclear wastes are:
i) Nuclear waste contains radioactive substances which emit harmful nuclear radiations.
ii) There is a high risk of environmental contamination.
iii) It is highly toxic.
Effect of nuclear waste on plant and animal life is:
The radiations emitted from the nuclear waste penetrate deep inside the human or animal body where they can damage biological cells thereby initiate cancer or causes genetic disease.
Increased mortality of plants, soil invertebrates and mammals and reproductive losses in plants and animals have also been observed.

Question. Why do people oppose the construction of Tehri Dam on the river Ganga and Sardar sarover project on the river Narmada. (Or)
Mention three disadvantage of producing hydroelectricity by constructing the dams.(Or) List any three ways in which construction of dams for production of electricity adversely affects the environment of that place.
Answer : 1. Large area is required to build the dam that result rehabilitation of displaced people.
2. Large eco-systems are destroyed when submerged under the water in dams.
3. The vegetation which is submerged rots under anaerobic conditions and gives rise to large amounts of methane gas which leads to a green-house effect.

Question. State any three reasons to justify that LPG is considered as an ideal fuel.
Answer : LPG is considered as an ideal fuel because
It is easy to store, handle and transport.
It produces large amount of heat on burning.
It does not leave any residue on burning,

Question. Solar cooker takes more time as compared to the LPG to boil potato or rice, yet Kunal uses solar cooker for such type of cooking:
(i) Why does Kunal uses Solar cooker instead of LPG? Give reasons for your Answer :
(ii) Name the phenomenon which is responsible for obtaining high temperature in solar cooker.
Answer : (a)(i) There are no energy losses while cooking on the solar cooker as the food gets cooked in a controlled environment whereas cooking on the LPG leads to maximum percentage of energy loss.
(ii) Temperature controlled cooking retains the nutrient value of the food.
(iii) Using the solar cooker, LPG can be served which result reduction in the emission of CO₂.
(iv) It saves a lot of prestigious time which is normally consumed for cooking purpose.
(b) Greenhouse effect.

Question. Define process of nuclear fission. Writ the steps involved in generating electricity in a nuclear reactor.
Answer : Nuclear Fission: The process in which a heavy nucleus (such as uranium, plutonium or thorium) is broken into two nearly equal fragments when bombarded with low-energy neutrons and a tremendous amount of energy is released. This process is called nuclear fission.
Steps involved in generating electricity:
1. The fuel rods full of uranium pellets are placed in a nuclear reactor chamber.
2. Low-energy neutrons are bombarded on uranium fuel rod.
3. A self-sustaining fission chain reaction starts that releases energy at a controlled rate.
4. With this heat the reactor converts water to steam at a high temperature and pressure.
5. This high temperature and pressure steam spins generator turbines producing electricity.
6. The steam cools back into water, which can then be used over again.

Question. Mention the purpose of blackening the interior of a solar cooker.
Answer : The purpose of blackening the interior of a solar cooker is that the black surface absorbs more heat radiations of incident solar energy (about 98%) as compare to white or other light coloured surface

Question. What are the advantages of nuclear energy?
Answer : Advantages of nuclear energy are:
• A small quantity of nuclear fuel is needed to produce a large amount of useful energy.
• Nuclear power plant produces less atmospheric pollution than thermal power plants, if the nuclear fission reaction is performed properly.
• Small amount of nuclear fuel can run a nuclear power plant over a long period of time.
There is no need of inserting the nuclear fuel in the nuclear reactor again and again in a short period as in case of thermal power plant.

Question. (a) Define tidal energy.
(b) Explain how the tidal energy is harnessed and write one limitation of the use of tidal energy.
Answer : (a) Tidal energy: The energy produced by the surge of ocean water during high and low tides due to difference in sea-levels is called tidal energy. The high and low tides occur due to the gravitational pull of the moon. This causes enormous movement of water.
(b) Tidal energy is harnessed by constructing a dam near the shores. During the high tides water flows into the dam and during the low tides, water flows out. This flowing water rotates the turbine, present at the opening of the dam and produces electricity.

Question. State any three advantages of charcoal over wood.
Answer : Advantages of charcoal over wood
It has higher calorific value, i.e. higher heat generating efficiency.
Charcoal does not produce smoke on burning so it is a clean fuel. It is easier to transport and ready to use in a convenient dry and broken-up form.

Question. State the principle of working of ocean thermal energy conversion plant.
Explain how the plant works? Write one essential condition for it to operate properly.
Answer : Principle of working of OTEC: The water at the surface of the ocean is warmer than the water at deeper depths. This temperature difference can be used by Ocean Thermal Energy Conversion (OTEC) systems to generate electricity. Working of OTEC:
• In OTEC plant, the energy of warm surface water is used to convert low i boiling point liquid ammonia into gaseous state.
• The vapour of ammonia at high pressure is used to spin the turbines of generators converting the Ocean thermal energy to electricity.
• The used vapour pass through the condenser where cold water, pumped from the deeper parts of ocean condenses ammonia vapour back into a liquid.
• This process is repeated again and again ,to get continuous production of electricity. Essential condition for it to operate properly: The temperature difference between the warmer water at the surface and colder water at depths up to 2 km should be 293 K (20°C) or more.

Question. Distinguish between renewable and non-renewable sources of energy. Also give an example of each of these sources.
Answer :

""CBSE-Class-10-Science-Sources-Of-Energy

Long Answer Type Questions

Question. What is biogas? Describe the working of a biogas plant with the help of a labelled diagram.

Answer : Biogas is a mixture of methane, carbon dioxide, hydrogen and hydrogen sulphide.

The major constituent of biogas is methane. Biogas is produced by the anaerobic degradation of animal wastes like cow-dung or plant wastes in the presence of water.

The biogas plant has a dome-like structure built with bricks. A slurry of cow-dung and water is made in the mixing tank from where it is fed into the digester. The digester is a sealed chamber in which there is no oxygen.

Anaerobic micro-organisms that do not require oxygen decompose or break down complex compounds of the cow-dung slurry. It takes a few days for the decomposition process to complete and generate gases. The biogas is stored in the gas tank above the digester from which they are drawn through pipes for use.

Question. Give the construction and working of a solar cooker.

Answer : A device that utilises solar energy for cooking purposes is called a solar cooker. The most commonly used form of solar cooker is known as box-type solar cooker. A box-type solar cooker is shown in the figure.

Construction of a box-type solar cooker:

A box-type solar cooker consists of the following components:

The food absorbs heat from the black surface and gets cooked. The thick glass sheet does not allow the heat produced to escape and thus, helps in raising the temperature in the box to a sufficiently high degree to cook the food.

i. Box (B): This is an insulated metal or a wooden box. It is painted black from inside because black surface absorbs more heat. The box may be provided with four rollwheels.

ii. Glass cover (G): A cover made of two sheets of toughened glass held together in an aluminium frame is used as a cover of the box B.

iii. Plane mirror reflector (R): A plane mirror reflector fixed in a frame is fixed to the box B with the help of hinges. The mirror reflector can be positioned at any desired angle to the box. The mirror is positioned so as to allow the reflected sunlight fall on the glass cover of the box.

iv. Cooking containers (C): A set of containers made of aluminium and blackened from outside are kept in the box B.
These containers are also painted black because black surface absorbs more heat.
Working:

The food is cooked in a shallow vessel of the container. The box has a transparent covering of glass sheet over it. The solar cooker is placed in sunlight and reflector (plane mirror) is adjusted in such a way that a strong beam of sunlight enters the box through the glass sheet. The blackened metal surfaces in the wooden box absorb infra-red radiations from the beam of sunlight and heat produced raises the temperature of blackened metal surface to about 100°C

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Worksheet for CBSE Science Class 10 Chapter 14 Sources of Energy

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