# Lakhmir Singh solutions for Class 10 Physics (Science) chapter 3 - Sources of Energy [Latest edition]

## Chapter 3: Sources of Energy

[Pages 112 - 123]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Pages 112 - 123]

Q 1 | Page 121

Name a non-renewable source of energy other than fossil fuels.

Q 2 | Page 121

Define calorific value of a fuel.

Q 3 | Page 121

"The calorific value of cooking gas (LPG) is 50 kJ/g". What does it mean?

Q 4 | Page 121

Which of the following produces more heat (per unit mass) on burning?

Q 5 | Page 122

Define ignition temperature of a fuel.

Q 6 | Page 122

"The ignition temperature of a fuel is 80°C". What does this mean?

Q 9 | Page 122

State any four characteristics of a good source of energy.

Q 10 | Page 112

What is meant by a non-renewable source of energy? Give two examples of non-renewable source of energy.

Q 11 | Page 122

What is meant by a renewable source of energy? Give two examples of renewable sources of energy.

Q 12 | Page 122

What is the difference between a renewable and a non-renewable source of energy? Explain with examples.

Q 13 | Page 122

Why are fossil fuels classified as non-renewable source of energy?

Q 14 | Page 122

Name two sources of energy that you think are renewable. Give reason for your choice.

Q 15 | Page 122

Name two sources of energy which you consider to be non-renewable. Give reason for your choice.

Q 16.1 | Page 122

Classify the following into renewable and non-renewable sources of energy:
Coal, Wind, Tides, Petroleum,Wood, Natural gas

Q 16.2 | Page 122

Classify the following

Coal, Wind, Tides, Petroleum,Wood, Natural gas

What is the basis of above classification?

Q 17 | Page 122

Coal is said to be formed from the wood of trees. Why then is coal considered to be a non-renewable source of energy whereas wood is a renewable source of energy?

Q 18.1 | Page 122

What is a fuel? Give five examples of fuels.

Q 18.2 | Page 122

What are the characteristics of an ideal fuel (or good fuel)?

Q 18.3 | Page 122

The calorific value and ignition temperature of fuel A are 55 kJ/g and 80°C, respectively. These values for fuel B are 80 kJ/g and 10°C, respectively. On burning, the fuel A produces CO2 and H2O while the fuel B produces CO2 , CO and SO2. Give three points of relative and disadvantages of these two fuels.

Q 19 | Page 122

An examples of a renewable source of energy is:

(a) petrol
(b) natural gas
(c) biogas
(d) kerosene

Q 20 | Page 122

A non-renewable source of energy is:

(a) wood
(b) alcohol
(c) hydrogen gas
(d) natural gas

Q 21 | Page 122

Which of the following is not a renewable source of energy?

(a) wind
(b) flowing water
(c) fossil fuels
(d) fuel wood

Q 22 | Page 122

A good fuel is one which possesses:

(a) high calorific value and low ignition temperature
(b) high calorific value and high ignition temperature
(c) high calorific value and moderate ignition temperature
(d) low calorific value and moderate ignition temperature

Q 23 | Page 122

The fuel having a calorific value of 55 kJ/g is likely to be:

(a) biogas
(b) methane gas
(c) hydrogen gas
(d) natural gas

Q 24 | Page 122

A newly planted sapling usually grows and matures into a tree in more than:

(a) 50 years
(b) 25 years
(c) 45 years
(d) 15 years

Q 25 | Page 122

Which of the following fuels has the highest calorific value?

(a) natural gas
(b) methane gas
(c) hydrogen gas
(d) biogas

Q 26 | Page 122

The fuel having the lowest calorific value is:

(a) coal
(b) wood
(c) charcoal
(d) kerosene

Q 27 | Page 123

There are four fuels which all contain only carbon and hydrogen. The fuel having highest calorific value will be one which has:

(a) more of carbon but less of hydrogen
(b) less of carbon but more of hydrogen
(c) equal proportions of carbon and hydrogen
(d) less of carbon as well as less of hydrogen

Q 28 | Page 123

One of the following is not a characteristic of a good fuel. This is:

(a) high calorific value
(b) no emission of smoke
(c) smooth burning
(d) high ignition temperature

Q 29 | Page 123

Which of the following is not a fossil fuel?

(a) coal
(b) petroleum gas
(c) biogas
(d) natural gas

Q 30 | Page 123

The calorific values of three fuels A, B and C are 33 kJ/g, 48 kJ/g and 150 kJ/g, respectively. A is solid, B is liquid and C is a gas at room temperature. One combustion, both A and B produce carbon dioxide while C explodes forming steam. B and C leave no residue after combustion while A leaves behind some solid residue. Which one of the three fuels is the most ideal? Give two reasons to support your answer.

Q 31 | Page 123

Calorific value and ignition temperature of fuel X are 75 kJ/g and 20°C respectively. These values for fuel Y are 50 kj/g and 75°C respectively. On burning, the fuel Y produces only CO2while fuel X produces CO2 and CO. Which of the two is a better fuel? Give two reasons to support your answer.

Q 32 | Page 123

The calorific values of five fuels A, B, C, D and E are given below:

 A 48KJ/g B 17KJ/g C 150KJ/g D 50KJ/g E 30KJ/g

Which of the fuels could be : (i) cooking gas (ii) alcohol (iii) wood (iv) hydrogen (v) kerosene?v
Q 33 | Page 123

Arrange the following fuels in the order of decreasing calorific values (keeping the fuel with highest calorific value first):
Biogas, Kerosene, Wood, Petrol, Hydrogen gas, Methane

Q 34 | Page 123

Arrange the following fuels in the order of increasing calorific values (keeping the fuel with lowest calorific value first):
LPG, Coal, Alcohol, Dung cakes, Diesel

Q 35 | Page 123

Most of the fuels contain carbon as one of the constituents. Name a fuel which has very high calorific value but not contain carbon.

[Pages 130 - 132]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Pages 130 - 132]

Q 1 | Page 130

Name the product of petroleum that is used to drive heavy vehicles.

Q 2 | Page 130

Give one example of a good domestic fuel.

Q 3 | Page 130

Name any one hydrocarbon fraction obtained during the fractional distillation of petroleum which is used as a domestic fuel.

Q 4 | Page 130

What are the various fuels which are used to generate electricity in a thermal power plant?

Q 5 | Page 130

Name any four fractions obtained from petroleum which are used as fuels.

Q 6 | Page 131

What is the composition of liquefied petroleum gas (LPG)?

Q 7 | Page 131

Which gaseous fuel is being used increasingly in transport vehicles like cars and buses these days?

Q 8 | Page 131

Write the full form of: (i) LPG, and (ii) CNG.

Q 9 | Page 131

What is the main constituent of:

(1) petroleum gas?
(2) natural gas?

Q 10 | Page 131

Name the component which is found in natural gas well as in biogas.

Q 11 | Page 131

State two important uses of natural gas

Q 12 | Page 131

State one important use of CNG these days.

Q 13 | Page 131

Complete the following sentence:

Domestic gas cylinders like Indane contain mainly ..............

Q 14 | Page 131

Explain why, natural gas is considered to be a good fuel.

Q 15 | Page 131

What is meant by conventional sources of energy? Write the names of two conventional sources of energy.

Q 16 | Page 131

Explain the principle of working of a thermal power plant. Draw labelled diagram to illustrate your answer.

Q 17 | Page 131

What are the disadvantages of burning fossil fuels?

Q 18 | Page 131

Write a short note on the pollution caused by burning fossil fuels.

Q 19 | Page 131

What are the various steps which can be taken to control (or reduce) pollution caused by burning fossil fuels?

Q 20 | Page 131

If you could use any source of energy for heating your food, which one would you use and why?

Q 21 | Page 131

Why is LPG considered a good fuel?

Q 22 | Page 131

Why is LPG considered a better fuel than coal?

Q 23 | Page 131

Why is the leakage of LPG detected easily although it is odourless? State the steps to be taken in case its leakage is detected in the kitchen.

Q 24.1 | Page 131

What are fossil fuels? Give three examples of fossil fuels.

Q 24.2 | Page 131

Describe how fossil fuels were formed.

Q 24.3 | Page 131

Explain how, sun is considered to be the ultimate source of fossil fuels

Q 24.4 | Page 131

Which fossil fuels were formed by the buried remains of small plants and animals?

Q 24.5 | Page 131

Which fossil fuel formed by the buried remains of large land plants?

Q 25 | Page 131

The main constituent of petroleum gas is:

(a) methane
(b) ethane
(c) butane
(d) propane

Q 26 | Page 131

The natural gas consists mainly of:

(a) methane
(b) ethane
(c) propane
(d) butane

Q 27 | Page 131

Which of the following is not produced by the burning of fossil fuels?

(a) nitrogen oxides
(b) sulphur oxides
(c) sodium oxides
(d) carbon oxides

Q 28 | Page 131

The product of petroleum used to drive heavy vehicles like trucks is:

(a) petrol
(b) kerosene
(c) diesel
(d) carbon oxide

Q 29 | Page 131

The aviation fuel which is used in the engines of jet aeroplanes is:

(a) diesel
(b) kerosene
(c) petrol
(d) CNG

Q 30 | Page 131

The ultimate source of energy stored in fossil fuels is:

(a) moon
(b) earth
(c) sun
(d) sea

Q 31 | Page 131

Which of the following is not a fossil source of energy?

(a) kerosene oil
(b) cow-dung cakes
(c) CNG
(d) coal

Q 32 | Page 131

The fuel which is not used at thermal power plants is:

(a) coal
(b) uranium
(c) natural gas
(d) fuel oil

Q 33 | Page 132

LPG consists mainly of:

(a) butane
(b) ethane
(c) butanone
(d) methane

Q 34 | Page 132

Coke is move valuable when used:

(a) as a fuel for industrial boilers
(b) as an oxidising agent
(c) as a reducing agent
(d) as a fuel in domestic ovens

Q 35 | Page 132

Coal cannot be converted into one of the following forms of energy. This is:

(a) coal gas
(b) electricity
(c) oil
(d) charcoal

Q 36 | Page 132

One of the following does not contribute to acid rain. That is:

(a) nitrogen monoxide
(b) sulphur dioxide
(c) carbon monoxide
(d) carbon dioxide

Q 37.1 | Page 132

Fossil fuels are energy rich compounds of an element X which were originally made by the plants with help of sun's energy.

Name the element X.

Q 37.2 | Page 132

Fossil fuels are energy rich compounds of an element X which were originally made by the plants with help of sun's energy.

Name another element which is usually found in combination with X in fossil fuels.

Q 38 | Page 132

The energy in petrol originally came from the sun. Explain how it got into petrol.

Q 39.1 | Page 132

A substance X is added to LPG cylinders while filling so as to make the detection of leakage of LPG from the cylinder easy.

Name the substance X.

Q 39.2 | Page 132

A substance X is added to LPG cylinders while filling so as to make the detection of leakage of LPG from the cylinder easy.

How does substance X make the detection of leakage of LPG easy?

Q 40.1 | Page 132

The pollution of air caused by burning petroleum fuels (like petrol and diesel) in vehicles can be controlled by fitting a device X in the exhaust system of vehicles.

Name the device

Q 40.2 | Page 132

The pollution of air caused by burning petroleum fuels (like petrol and diesel) in vehicles can be controlled by fitting a device X in the exhaust system of vehicles.

How does this device help in controlling air pollution?

[Pages 122 - 142]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Pages 122 - 142]

Q 1 | Page 140

A hydro-power plant converts one form of energy into another. Name the two forms of energy.

Q 2 | Page 140

What type of energy is possessed by flowing water?

Q 3 | Page 140

Flowing water can rotate a turbine. Which type of energy is used up by the turbine?

Q 4 | Page 140

Name the original source of wind energy.

Q 5 | Page 140

What should be the minimum wind speed for the satisfactory working of a wind-powered electric generator?

Q 6.1 | Page 140

Write one use of wind energy

(a) in the past

Q 7 | Page 122

Fill in the following blank with a suitable word:

The amount of heat produce by burning a unit mass of a fuel completely is known as its ............ value.

Q 7 | Page 140

Why is the copper tube of a solar water heater painted black from outside?

Q 8 | Page 122

What is a source of energy? What are the two main categories of the sources of energy?

Q 8 | Page 140

What type of reactions occurring inside the sun produce solar energy?

Q 9 | Page 140

Name some of the solar energy devices.

Q 10 | Page 140

What type of reflector is used in a box-type solar cooker?

Q 11 | Page 140

What is the range of temperature which can be achieved in a box-type solar cooker in two to three hours?

Q 11 | Page 140

What is the range of temperature which can be achieved in a box-type solar cooker in two to three hours?

Q 12 | Page 140

Name the device which converts sunlight into electricity.

Q 13 | Page 140

How much solar energy will be received by 1 m2 area in one hour if the solar constant be 1.4 kW/m2?

Q 14 | Page 140

Fill in the following blank with suitable word:
A solar cell converts ................ energy into ................ energy.

Q 15.1 | Page 140

What is the difference between a thermal power plant and a hydro power plant?

Q 15.2 | Page 140

Which of the two causes serious air pollution and how?

Q 16 | Page 141

Compare the sun and the fossil fuels as the sources of energy.

Q 17 | Page 141

What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?

Q 18.1 | Page 141

Name that part of a box-type solar cooler which allow the sun's heat rays to enter the box but does not allow inside heat to go out.

Q 18.2 | Page 141

Explain why, a plane mirror reflector is used in a box-type solar cooker.

Q 19 | Page 141

What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?

Q 20.1 | Page 141

What is a solar cell? Draw the labelled diagram of a solar cell.

Q 20.2 | Page 141

Name the semi-conductor material which is usually used for making solar cells.

Q 20.3 | Page 141

Write the uses of solar cells.

Q 21 | Page 141

Q 22 | Page 141

What is a solar cell panel? For what purpose is it used? State its two main advantages.

Q 23.1 | Page 141

What is solar constant? What is the value of solar constant?

Q 23.2 | Page 141

If the energy received by 5 m2 area in 10 minutes is 4200 kJ, calculate the value of solar constant.

Q 24 | Page 141

How has the traditional use of energy of flowing water been modified for our convenience?

Q 24 | Page 141

How has the traditional use of energy of wind energy been modified for our convenience?

Q 26.1 | Page 141

What is hydroelectricity? Explain the basic principle of generation of hydroelectricity with the help of a labelled diagram.

Q 26.2 | Page 141

State two advantages of producing hydroelectricity.

Q 26.3 | Page 141

State two disadvantages of producing hydroelectricity.

Q 27.1 | Page 141

With the help of a labelled diagram, explain the construction and working of a solar cooker.

Q 27.2 | Page 141

Why is the solar cooker box painted black from inside?

Q 27.3 | Page 141

Why is the solar cooker box covered with a glass sheet?

Q 28.1 | Page 141

What is wind? What type of energy is possessed by wind?

Q 28.2 | Page 141

Explain how, wind energy can be used to generate electricity. Illustrate your answer with the help of a labelled diagram.

Q 28.3 | Page 141

State two advantages of using wind energy for generating electricity.

Q 28.4 | Page 141

Mention two limitations of wind energy for generating electricity.

Q 29 | Page 141

A solar water heater cannot be used to get hot water on

• a sunny day

• a cloudy day

• a hot day

• a windy day

Q 30 | Page 141

At a hydro power plant:

(a) kinetic energy possessed by stored water is converted into electrical energy
(b) electrical is extracted from water
(c) water is converted into steam to turn turbines and produce electricity.
(d) potential energy possessed by stored water is converted into electricity.

Q 31 | Page 141

The part of box-type solar cooker which is responsible for producing greenhouse effect is:

(a) plane mirror reflector
(b) black coating inside the box
(c) glass sheet cover
(d) utensils placed in the cooker box

Q 32 | Page 141

(a) conductors
(b) insulators
(c) semi-conductors
(d) super-conductors

Q 33 | Page 141

The value of solar constant is:

(a) 1.4 kWh
(b) 1.4 kW/m
(c) 1.4 kW/m2
(d) 1.4 kW/m3

Q 34 | Page 141

The radiations present in sunlight which make a solar cooker work are:

(a) visible light rays
(b) ultraviolet rays
(c) comic rays
(d) infrared rays

Q 35 | Page 141

In order to make an efficient solar cooker, the cover of cooker box should be made of:

(a) transparent plastic sheet
(b) shining aluminium sheet
(c) butter paper sheet
(d) transparent glass sheet

Q 36 | Page 142

The minimum speed of wind necessary for the satisfactory working of a wind generator to produce electricity is about:

(a) 15 km/h
(b) 25 km/h
(c) 35 km/h
(d) 45 km/h

Q 37 | Page 142

If the solar constant is 1.4 kW/m2 then solar energy recived by 1m2area in one hour is:

(a) 5040 J
(b) 504.0 kJ
(c) 5040 kJ
(d) 5.04 kJ

Q 38 | Page 142

A solar cooker may not cook food if

(a) the solar cooker is not placed in the shade
(b) the glass sheet cover of solar cooker is not closed
(c) a convex mirror reflector is not used

Q 39.1 | Page 142

A large coal-fired power station produces 2000 MW of electrical energy. A wind turbine with 33 m blades can produce 300 kW.

How many turbines would be needed to replace the power station?

Q 39.2 | Page 142

A large coal-fired power station produces 2000 MW of electrical energy. A wind turbine with 33 m blades can produce 300 kW.

Why, in actual practice, this number of turbines could not replace the coal-fired power station?

Q 40 | Page 142

In a solar water heater, why is the storage tank placed at a higher lever than the solar panel containing coils?

Q 41 | Page 142

In many applications, solar cells are connected to rechargeable batteries. Why is this so?

Q 41.1 | Page 142

Solar cells are used to provide the electric current to charge the batteries of a car driven by an electric motor. Describe the energy changes which take place.

Q 42.2 | Page 142

What differences would you expect in the charging of car batteries (i) in bright sunlight (ii) on a cloudy day (iii) at night?

[Pages 148 - 150]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Pages 148 - 150]

Q 1 | Page 148

What substance is obtained as a residue when wood is burned in a limited supply of air?

Q 2 | Page 148

Name one source of energy which is not derived from solar energy directly of indirectly.

Q 3 | Page 148

What name is given to the heat energy obtained from hot rocks inside the earth?

Q 4 | Page 148

Name the agent which decomposes animal dung into biogas.

Q 5 | Page 148

Which component of biogas is used as a fuel?

Q 6 | Page 148

Name the constituents of biogas.

Q 7 | Page 148

Which of the following is needed for the formation of biogas from cow-dung and which not?
Water, Oxygen

Q 8 | Page 148

Name the clean fuel which can be obtained from cow-dung.

Q 9 | Page 148

Apart from cattle dung, what other substances can be added to a biogas plant?

Q 10 | Page 148

Name any three forms of energy which could be harnessed from the sea.

Q 11 | Page 148

Write two forms in which solar energy manifests itself in sea.

Q 12 | Page 148

Write the full from of OTE.

Q 13 | Page 148

What is the function of anaerobic micro-organisms such as anaerobic bacteria in a biogas plant?

Q 14 | Page 148

State whether the following statement is true or false:
Tidal energy is one of the forms in which solar energy manifests itself in oceans.

Q 15.1 | Page 148

Fill in the following blank with suitable word:

Biomass is another form in which ........... energy manifests itself.

Q 15.2 | Page 148

Fill in the following blank with suitable word:

Tidal waves build up and recede ........... a day.

Q 16.1 | Page 148

What is biomass? Give three examples of biomass.

Q 16.2 | Page 148

Name the biomass which is still widely used as a source of heat energy in many household of our country.

Q 17 | Page 148

What are the two ways in which cow-dung can be used as a fuel? Which of them is better and why?

Q 18 | Page 149

How is charcoal prepared? Explain why, charcoal is a better fuel than wood.

Q 19 | Page 149

Compare and contrast biomass and hydroelectricity as sources of energy.

Q 20 | Page 149

Why is biogas considered an ideal fuel for domestic use?

Q 21.1 | Page 149

Explain how tidal energy can used to generate electricity?

Q 21.2 | Page 149

Why is tidal energy not likely to be a potential source of energy?

Q 22 | Page 149

State two ways in which the energy of sea-waves can be harnessed.

Q 23 | Page 149

What is meant by ocean thermal energy? Explain how ocean thermal energy can be used to generate electricity.

Q 24 | Page 149

What are the limitations of energy that can be harnessed from the sea?

Q 25 | Page 149

Suggest a safe and efficient method for the disposal of biowastes and sewage materials. How is this method advantageous to us?

Q 26 | Page 149

Which of the following sources of energy are not derived from the sun?
Biomass, Wind, Ocean thermal energy, Geothermal energy, Nuclear fuels, Hydroelectricity, Wave energy, Coal, Petroleum, Tidal energy

Q 27.1 | Page 149

What is biogas?

Q 27.2 | Page 149

Name the major component of biogas.

Q 27.3 | Page 149

What are the raw materials used for making biogas?

Q 27.4 | Page 149

Describe the construction and working of a biogas plant with the help of a labelled diagram.

Q 27.5 | Page 149

Write any two uses of biogas.

Q 27.6 | Page 149

Write any two advantages of using biogas.

Q 28.1 | Page 149

What is geothermal energy?

Q 28.2 | Page 149

What is the source of heat contained in geothermal energy?

Q 28.3 | Page 149

Explain how, geothermal energy is used to generate electricity.

Q 28.4 | Page 149

State two advantages of geothermal energy.

Q 28.5 | Page 149

State two disadvantages of geothermal energy.

Q 29 | Page 149

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

(a) wood
(b) biogas
(c) atomic energy
(d) cow-dung

Q 30 | Page 149

Most of the sources of energy that we sue represent stored solar energy. Which of the following is not ultimately derived from the sun's energy?

(a) wind energy
(b) geothermal energy
(c) fossil fuels
(d) biomass

Q 31 | Page 149

The constituent of biogas which makes it an excellent fuel is:

(a) butane
(b) methane
(c) propane
(d) ethane

Q 32 | Page 149

The major component of biogas is:

(a) hydrogen
(b) butane
(c) hydrogen sulphide
(d) methane

Q 33 | Page 149

Which of the following is more environment friendly??

(a) burning of diesel
(b) burning of coal
(c) burning of charcoal
(d) burning of wood

Q 34 | Page 149

Which one of the following is not renewable energy technology?

(a) solar cells
(b) windmills
(c) nuclear power
(d) tidal power

Q 35 | Page 149

The rise of sea-water during high tide is caused by the gravitational pull of the:

(a) Sun
(b) Earth
(c) Moon
(d) Mars

Q 36 | Page 149

One of the following is not required in the formation of biogas in a biogas plant. This is:

(a) cow-dung
(b) water
(c) oxygen
(d) anaerobic bacteria

Q 37 | Page 149

The fuel which is not obtained from biomass is:

(a) firewood
(b) cow-dung cakes
(c) coke
(d) charcoal

Q 38 | Page 149

The non-renewable source of energy among the following is:

(a) hydroelectricity
(b) sewage gas
(c) natural gas
(dgobar gas

Q 39 | Page 149

Geothermal energy is produced by the:

(b) burning of coal inside the coal mines
(c) combustion of natural gas deep inside the earth

Q 40 | Page 150

The harnessing of which of the following leads to the destruction of large eco-systems?

(a) thermal power
(b) tidal power
(c) hydro power
(d) geothermal power

Q 41 | Page 150

The harnessing of which of the following leads to the destruction of large eco-systems?

(a) thermal power
(b) tidal power
(c) hydro power
(d) geothermal power

Q 42 | Page 149

A certain form of energy is available due to the difference in the temperature of water at the surface of the ocean and its deeper levels.

(a) Name the form of energy.
(b) Is this energy ultimately derived from the sun or not?
(c) Explain how this form of energy can be converted into electricity.
(d) What is the minimum temperature difference in water at the surface of ocean and its deeper level which is required to operate power plants based on is energy?

Q 43 | Page 149

The gravitational pull of the moon cause the sea-water to rise periodically.

(a) What name is given to the condition of the sea when water to rise periodically.
(b) What name is given to the condition of the sea when its raised water recedes?
(c) What name is given to the energy which can be harnessed from this natural phenomenon?
(d) Draw labelled diagram to show how this energy can be harnessed from this natural

Q 44 | Page 150

When the material A mined from the earth is heated strongly in an insufficient supply of air, it produces a solid fuel B which consists mainly of carbon. When another material C obtained from trees is heated in an insufficient supply of air, it produces another solid fuel D which also consists mainly of carbon. Name A, B, C and D

Q 45 | Page 150

A certain form of energy which is not sourced directly or indirectly from the sun and does not cause any pollution is very easily converted into electricity. This form of energy is, however, not available everywhere. Moreover, it is technically very difficult and expensive to obtain it. Name the form of energy.

[Pages 156 - 159]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Pages 156 - 159]

Q 1.1 | Page 156

What type of nuclear reaction is responsible for the liberation of energy:

in a nuclear reactor?

Q 1.2 | Page 156

What type of nuclear reaction is responsible for the liberation of energy:

in the sun?

Q 2 | Page 156

Which produced of the nuclear fission of uranium-235 is utilised to cause further fission of its nuclei?

Q 3 | Page 156

Which particles bring about the fission of uranium-235?

Q 4 | Page 156

State whether the fission of uranium-235 is caused by low energy neutrons or high energy neutrons.

Q 5.1 | Page 156

Name the type of nuclear reaction which is involved in the working of:

a hydrogen bomb.

Q 5.2 | Page 156

Name the type of nuclear reaction which is involved in the working of:

an atom bomb.

Q 6 | Page 156

Name the moderator used in a nuclear reactor.

Q 7 | Page 156

Of what material are the control rods of a nuclear reactor made?

Q 8 | Page 156

What do you think is the purpose of the thick, concrete chamber surrounding the reactor of a nuclear power plant?

Q 9 | Page 157

Where, in a nuclear power station, is uranium used up?

Q 10 | Page 157

State one use of nuclear fission reactions.

Q 12 | Page 157

How many MeV are equivalent to 1 atomic mass unit (u)?

Q 13.1 | Page 157

Fill in the following blank with suitable word:

Splitting of a heavy nucleus into two lighter nuclei is called ........

Q 13.2 | Page 157

Fill in the following blank with suitable word:

Uranium-235 atoms will split when hit by .......... This is called ...........

Q 13.3 | Page 157

Fill in the following blank with suitable word:

Nuclear .......... is used in nuclear power stations for the production of electricity.

Q 13.5 | Page 157

Fill in the following blank with suitable word:

In a nuclear power station, nuclear fission takes place in the .............

Q 14 | Page 157

What is nuclear fission? Explain with an example. Write the equation of the nuclear reaction involved.

Q 15.1 | Page 157

What is nuclear fusion? Explain with an example. Write the equation of the reaction involved.

Q 15.2 | Page 157

Why are very high temperatures required for fusion to occur?

Q 16.1 | Page 157

What is the nuclear fuel in the sun ?

Q 16.2 | Page 157

Describe the process by which energy is released in the sun. Write the equation of the nuclear reaction involved.

Q 17.1 | Page 157

Write Einstein's mass-energy equation. Give the meaning of each symbol  which occurs in it.

Q 17.2 | Page 157

If 25 atomic mass units (u) of a radioactive material are destroyed in a nuclear reaction, how much energy is released in MeV?

Q 18.1 | Page 157

What is the source of energy of the sun and other stars?

Q 18.2 | Page 157

Describe the working of a hydrogen bomb.

Q 18.2 | Page 157

What is common between the sun and a hydrogen bomb?

Q 19.1 | Page 157

What will happen if slow moving neutrons are made to strike the atoms of a heavy element  ''235_92U? What is the name of this process?

Q 19.3 | Page 157

Name one installation where such a process is utilised.

Q 20.1 | Page 157

What are the advantages of nuclear energy?

Q 20.2 | Page 157

State the disadvantages of nuclear energy?

Q 21.1 | Page 157

The following question are about the nuclear reactor of a power plant.

Which isotope of uranium produces the energy in the fuel rods?

Q 21.2 | Page 157

The following question are about the nuclear reactor of a power plant.

Will the fuel rods last for ever?

Q 21.3 | Page 157

The following question are about the nuclear reactor of a power plant.

Is the energy produced by nuclear fission or nuclear fusion?

Q 21.4 | Page 157

The following question are about the nuclear reactor of a power plant.

What is the purpose of using the graphite moderator?

Q 21.5 | Page 157

The following question are about the nuclear reactor of a power plant.

What is the function of boron rods in the nuclear reactor?

Q 21.6 | Page 157

The following question are about the nuclear reactor of a power plant.

Why is liquid sodium (or carbon dioxide gas) pumped through the reactor?

Q 22 | Page 157

In the reactor of a nuclear power plant, name the material which is used:

(a) as a moderator
(c) in the fuel rods
(d) in the control rods
(e) to carry away heat

Q 23.1 | Page 157

In the nuclear reactor of a power plant:

how do control rods control the rate of fission?

Q 23.2 | Page 157

how is heat removed from the reactor core, and what use is made of this heat?

Q 24 | Page 157

How does inserting the control rods in the graphite core affect the fission in the reactor? Explain your answer.

Q 25 | Page 157

What are the advantages and disadvantages of using nuclear fuel for generating electricity?

Q 26.1 | Page 157

What is a nuclear reactor? What is the fuel used in a nuclear reactor?

Q 26.2 | Page 157

With the help of a labelled diagram, describe the working of a nuclear power plant

Q 26.3 | Page 157

How is the working nuclear reactor of a power plant shut down in an emergency?

Q 26.5 | Page 157

Name five places in India where nuclear power plants are located.

Q 27.1 | Page 158

Differentiate between nuclear fission and nuclear fusion.

Q 27.2 | Page 158

Which of the two, nuclear fusion and nuclear fusion,  is made use of:
(1) for the production of electricity?
(2) for making a hydrogen bomb?

Q 27.3 | Page 158

Which produces more energy : nuclear fusion or nuclear fission?

Q 27.4 | Page 158

Calculate the energy released in joules when 5 g of a material is completely converted into energy doing a nuclear reaction.

Q 27.5 | Page 158

How much is this energy in MeV? (Speed of light = 3 × 108 m/s)

Q 28 | Page 158

Which of the following is used as a moderator in the reactor of a nuclear power station?

(a) liquid sodium
(b) boron
(c) graphite
(d) carbon dioxide

Q 29 | Page 158

The control rods used in the reactor of a nuclear power plant are made of:

(a) steel
(b) graphite
(c) uranium
(d) boron

Q 30 | Page 158

The 'coolants' which can be used in the reactor of a nuclear power station are:

(a) liquid mercury and nitrogen dioxide
(b) liquid sodium and carbon dioxide
(c) liquid ammonia and carbon monoxide
(d) liquid boron and uranium oxide

Q 31 | Page 158

In a nuclear power plant, coolant is a substance:

(a) which cools the hot, spent steam to condense it back to water
(b) which transfers heat from reactor to water in heat exchanger
(c) which is boiled to make steam to turn the turbine
(d) which cools the generator coils to prevent their overheating.

Q 32 | Page 158

Which of the following is ultimately not derived from the sun's energy (or solar energy)?

(a) wind energy
(b) nuclear energy
(c) biomass energy
(d) ocean thermal energy

Q 33 | Page 158

One atomic mass unit (u) is equivalent to an energy of:

(a) 931 eV
(b) 9.31 MeV
(c) 1 MeV
(d) 931 MeV

Q 35 | Page 158

One eV (electron volt) of nuclear energy is equivalent of:

(a) 1.6 × 10−14 J
(b) 1.6 × 10−12 J
(c) 1.6 × 10−19 J
(d) 1.6 × 10−13 J

Q 36 | Page 157

Which of the following can be produced during the nuclear fission as well as nuclear fusion reactions?

(a) protons
(b) deutrons
(c) electrons
(d) neutrons

Q 37 | Page 158

Nuclear fission reactions are not a source of energy for one of the following. This is:

(a) atom bomb
(b) power plants
(c) sun
(d) pacemaker

Q 38 | Page 158

The energy produced by converting 1 gram mass of a nuclear fuel into energy completely is:

(a) 9 × 1016 J
(b) 9 × 1014 J
(c) 9 × 1015 J
(d) 9 × 1013 J

Q 39 | Page 158

The source of energy of the sun is:

(a) conversion of hydrogen gas into helium
(b) conversion of carbon fuel into carbon dioxide
(c) burning of hydrogen gas present in the sun
(d) disintegration of uranium into barium and krypton

Q 40 | Page 158

An uncontrolled nuclear chain reaction forms the basis of:

(a) nuclear power plant
(b) hydrogen bomb
(c) thermal power station
(d) atom bomb

Q 41 | Page 158

One MeV of nuclear energy is equivalent to:

(a) 1.6 × 10−13 J
(b) 1.6 × 10−19 J
(c) 1.6 × 10−16 J
(d) 1.6 × 10−15 J

Q 42 | Page 158

One type of energy which has not been controlled so far is:

(a) ocean thermal energy
(b) nuclear fusion energy
(c) geothermal energy
(d) nuclear fission energy

Q 44 | Page 159

The heat energy released during nuclear fission and fusion is due to the:

(a) conversion of stored chemicals into energy
(b) conversion of momentum into energy
(c) conversion of mass into energy
(d) conversion of magnetism into energy

Q 45 | Page 159

The disposal of waves produced in a nuclear power plant poses a big problem because it is:

(a) too heavy
(b) highly inflammable
(c) extremely foul smelling

Q 45 | Page 159

Which of the following can undergo nuclear fusion reaction?

(a) uranium
(b) deuterium
(c) barium
(d) krypton

Q 46.1 | Page 159

A nuclear reaction is represented by the following equation:

""_92^235U+_0^1n-> _56^139Ba+_36^94Kr+xc+E

Name the process represented by this equation and describe what takes place

Q 46.2 | Page 159

A nuclear reaction is represented by the following equation:

""_92^235U+_0^1n-> _56^139Ba+_36^94Kr+xc+E

Identify the particle c and the number x of such particles produced in the reaction.

Q 46.3 | Page 159

A nuclear reaction is represented by the following equation:

""_92^235U+_0^1n-> _56^139Ba+_36^94Kr+xc+E

What does E represent?

Q 46.4 | Page 159

A nuclear reaction is represented by the following equation:

""_92^235U+_0^1n-> _56^139Ba+_36^94Kr+xc+E

Name one installation where the above nuclear reaction is utilised.

Q 46.5 | Page 159

A nuclear reaction is represented by the following equation:

""_92^235U+_0^1n-> _56^139Ba+_36^94Kr+xc+E

What type of bomb is based on similar type of reaction?

Q 47.1 | Page 159

A nuclear reaction is represented by the equation:

""_1^2H+_1^2H->_2^3He+xc+E

Name the process represented by this equation and describe what happens during this reaction.

Q 47.2 | Page 159

A nuclear reaction is represented by the equation:

""_1^2H+_1^2H->_2^3He+xc+E

Identify the particle c and the number x of such particles produced in the reaction.

Q 47.3 | Page 159

A nuclear reaction is represented by the equation:

""_1^2H+_1^2H->_2^3He+xc+E

What does E represent?

Q 47.4 | Page 159

A nuclear reaction is represented by the equation:

""_1^2H+_1^2H->_2^3He+xc+E

State two conditions under which such a reaction takes place.

Q 47.5 | Page 159

A nuclear reaction is represented by the equation:

""_1^2H+_1^2H->_2^3He+xc+E

What type of nuclear bomb is based on similar reactions?

Q 48.1 | Page 159

The mass numbers of four elements A, B, C and D are 2, 20, 135 and 235, respectively. Which one of them will be most suitable to make:

(i) an atom bomb,

Q 48.2 | Page 159

The mass numbers of four elements A, B, C and D are 2, 20, 135 and 235, respectively. Which one of them will be most suitable to make:

a hydrogen bomb?

Q 49 | Page 156

A nuclear power plant is working normally. What would you do if the reactor core suddenly got too hot?

Q 50 | Page 159

A nuclear reactor has half the length of all its control rods inserted in graphite. What must be done so that the reactor produces more heat? Explain your answer.

Q 51 | Page 159

Explain why, in a nuclear reactor, the chain reaction stops if the control rods are fully inserted into the graphite.

[Page 161]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Page 161]

Q 1 | Page 161

Which of the two is a cleaner fuel: hydrogen of CNG? Why?

Q 2 | Page 161

Which of the two is more energy efficient: filament type electric bulb or CFL? Why?

Q 3 | Page 161

How long are the energy resources of the earth like coal, petroleum and natural gas expected to last?

Q 4 | Page 161

Name two devices which can be utilised for the cooking of food so as to save fuel.

Q 5 | Page 161

What are the various factors which we should keep in mind while choosing a source of energy?

Q 6 | Page 161

Can any source of energy be pollution free? Explain your answer with an example.

Q 7 | Page 161

What are the environmental consequences of the increasing demand for energy?

Q 8 | Page 161

What steps would you suggest to reduce energy consumption?

Q 9 | Page 161

The major cause of environmental pollution is the use of:

(a) hydrogen as fuel
(b) biomass energy
(c) ocean energy
(d) fossil fuels

Q 10 | Page 161

The world's known coal reserves are expected to last for about:

(a) 200 years
(b) 400 years
(c) 500 years
(d) 100 years

Q 11 | Page 161

The fossil fuel whose known reserves in the earth are expected to last for the minimum period is:

(a) coal
(b) uranium
(c) petroleum
(d) natural gas

Q 12 | Page 161

An energy efficient devices for producing light is:

(a) DLF
(b) CFL
(c) FCL
(d) LPG

[Page 158]

### Lakhmir Singh solutions for Class 10 Physics (Science) Chapter 3 Sources of Energy [Page 158]

Q 34 | Page 158

The energy in the reactor of a nuclear power station is produced by the process of:

(a) nuclear diffusion
(b) nuclear fission
(c) nuclear fusion
(d) nuclear fermentation

## Lakhmir Singh solutions for Class 10 Physics (Science) chapter 3 - Sources of Energy

Lakhmir Singh solutions for Class 10 Physics (Science) chapter 3 (Sources of Energy) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Class 10 Physics (Science) solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 10 Physics (Science) chapter 3 Sources of Energy are Good Source of Energy, Different Forms of Energy, Conventional Sources of Energy, Conventional Sources of Energy - Thermal Power Plant, Conventional Sources of Energy - Hydro Power Plants, Improvements in the Technology for Using Conventional Sources of Energy, Alternative or Non-conventional Sources of Energy - Solar Energy, Alternative or Non-conventional Sources of Energy - Energy from the Sea, Alternative Or Non-conventional Sources of Energy - Geothermal Energy, Alternative or Non-conventional Sources of Energy - Nuclear Energy, Environmental Consequences, Energy Source - How Long Will Last Us, Renewable Versus Non-renewable Sources, Sources of Energy Introduction.

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