Solution of Chapter 3. Sources of Energy (Lakhmir Singh & Manjit Kaur - Physics Book)

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

Define calorific value of a fuel.

“The calorific value of cooking gas (LPG) is 50 kj/g”. What does it mean?

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

Define ignition temperature of a fuel.

“The ignition temperature of a fuel is 800 C”. What does this mean?

Fill in the following blank with a suitable word:

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

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

State any four characteristic of good sources of energy.

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

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

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

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

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

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

Classify the following into renewable and non-renewable sources of energy:

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

Non- Renewable source of energy - coal, petroleum, natural gas.

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

What is a fuel? Give five examples of fuels.

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

The calorific value and ignition temperature of fuel A are 55 kJ/g and 80oC, 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 advantages and disadvantages of these two fuels.

An example of a renewable sources of energy is :

A non-renewable sources of energy is:

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

A good fuel is one which process :

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

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

Which of the following fuels has the high calorific value ?

The fuel having the lowest calorific value is?

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

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

Which of the following is not a fossil fuel?

The calorific values of three fuels A, B and C are 33 KJ/g, 150 KJ/g, respectively. A is solid, B is liquid and C is a gas at room temperature. On combustion, both A and B produces 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.

Calorific value and ignition temperature of fuel X are 75 kJ/g and 200C respectively. These values for fuel Y are 50 kJ/g and 750C respectively. On burning, the fuel Y produces only CO₂ while fuel X produces CO₂ and CO. Which of the two is a better fuel? Give two reasons to support your answer.

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

(A) 48 kJ/g

(B) 17 kJ/g

(C) 150 kJ/g

(D) 50 kJ/g

(E) 30kJ/g

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

Arrange the following fuels in the order of decreasing calorific values (keeping the fuels with highest calorific value first):

Biogas, Kerosene, Wood, Petrol, Hydrogen gas, Methane

Arrange the following fuels in order of increasing calorific values (keeping the fuels with lowest calorific value first):

LPG, Coal, Alcohol, Dung cakes, Diesel

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

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

Give one example of a good domestic fuel.

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

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

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

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

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

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

What is the main constituent of:

(i) Petroleum gas

(ii) Natural gas

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

State two important uses of natural gas.

State one important use of CNG these days.

Complete the following sentence:

Domestic gas cylinders like Indanecontain mainly ………………….

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

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

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

What is the disadvantage of burning fossil fuels?

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

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

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

Why is LPG considered a good fuel?

Why is LPG considered a better fuel than coal?

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

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

Describe how fossil fuels were formed.

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

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

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

The main constituent of petroleum gas is:

The natural gas consist mainly of:

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

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

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

The ultimate sources of energy stored in fossil fuels is:

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

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

LPG consists mainly of:

Coke is more valuable when used

Coal is more valuable when used:

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

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

(a) Name the element X

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

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

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

(a) Name the substance X

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

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.

(a) Name the device X

(b) How does this device help in controlling air pollution ?

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

What type of energy is possessed by flowing water?

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

Name the original source of wind energy.

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

Write one use of wind energy

(a) In the past

(b) At present.

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

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

Name some of the solar energy devices.

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

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

Name the devices which converts sunlight into electricity.

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

Fill in the following blanks with suitable words :

A solar cell converts …………………. energy into …………………. energy.

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

Which of the two causes serious air pollution and how?

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

What kind of mirror, concave, convex or plane, would be best suitable for use in a solar cooker? why?

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

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

What are the advantages and disadvantage of using a solar cooker?

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

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

Write the uses of solar cells.

State the advantage and disadvantage of using solar cells.

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

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

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

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

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

What is hydro electricity? Explain the basic principle of generation of hydroelectricity with the help of a labeled diagram.

State two advantage of producing hydroelectricity.

State two disadvantage of producing hydroelectricity.

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

Why is the solar cooker box painted black from inside?

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

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

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

State two advantage of using wind energy for generating electricity.

Mention two limitations of wind energy for generating electricity.

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

At a hydro power plant:

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

Solar cells are made of:

The value of solar constant is

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

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

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

If the solar constant is 1.4 kW/m², then the solar energy received by 1 m² area in one hour is :

A solar cooker may not cook food if :

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

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

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

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

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

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.

What difference would you expect in the charging of car battries

(i) in bright sunlight

(ii) on a cloudy day

(iii) at night?

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

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

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

Name the agent which decomposes animal dung into biogas.

Which component of biogas is used as a fuel?

Name the constituents of biogas.

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

Water, Oxygen

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

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

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

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

Write the full form of OTE.

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

State whether the following statement is true or false:

Tidal energy is one of the forms in which solar energy manifests itself in oceans.

Fill in the following blanks with suitable words:

(a) Biomass is another form in which .......... energy manifests itself.

(b) Tidal waves build up and recede .............. a day.

What is biomass? Give three examples of biomass.

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

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

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

Compare and contrast biomass and hydroelectricity as sources of energy.

Why biogas is considered an ideal fuel for domestic use?

Explain how tidal energy can be used to generate electricity.

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

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

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

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

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

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

What is biogas? Name the major component of biogas.

What are the raw materials used for making biogas?

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

Write any two uses of biogas.

Write any two advantages of using biogas.

What is geothermal energy?

What is the source of heat contained in geothermal energy?

Explain how, geothermal energy is used to generate electricity.

State two advantages of geothermal energy.

State two disadvantages of geothermal energy.

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

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

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

The major component of biogas is :

Which of the following is more environment friendly ?

Which one of the following is not renewable energy technology?

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

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

The fuel which is not obtained from biomass is:

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

Geothermal energy is produced by the:

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

Which of the following is not a consequence of establishing hydroelectric power plants ?

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 this energy ?

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

(a) What name is given to the condition of the sea when its water is raised?

(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 to generate electricity.

When the material A mined from the earth ,is heated strongly in an insufficeint 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.

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.

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

(a) In a nuclear reactor?

(b) In the sun?

Which product of the nuclear fission of uranium-235 is utilized to cause further fission of its nuclei?

Which particles bring about the fission of uranium-235?

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

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

(a) A hydrogen bomb.

(b) An atom bomb.

Name the moderator used in a nuclear reactor.

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

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

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

State one use of nuclear fission reactions.

Name the unit which is commonly used for expressing the energy released in nuclear reactions.

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

Fill in the following blanks with suitable words:

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

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

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

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

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

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

Why are very high temperatures required for fusion to occur?

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

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

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

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

Describe the working of a hydrogen bomb.

What is common between the sun and a hydrogen bomb?

What will happen if slow moving neutrons are made to strike the atoms of a heavy element 23592U? What is the name of this process?

Write a nuclear equation to represent the process which takes place.

Name one installation where such a process is utilized.

What are the advantages of nuclear energy?

State the disadvantages of nuclear energy.

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

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

b) Will the fuel rods last forever?

c) Is the energy produced by nuclear fission or nuclear fusion?

d) What is the purpose of using the graphite moderator ?

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

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

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

(a) As a moderator

(b) To absorb radiations

(c) In the fuel rods

(d) In the control rods

(e) To carry away heat

In the nuclear reactor of a power plant:

(a) How do control rods control the rate of fission?

(b) How is heat removed from the reactor core, and what use is made of this heat?

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

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

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

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

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

Name five places in India where nuclear power plants are located

Differentiate between nuclear fission and nuclear fusion.

Which of the two, nuclear fission and nuclear fusion, is made use of:

(i) for the production of electricity?

(ii) for making a hydrogen bomb?

Which produces more energy: nuclear fusion or nuclear fission?

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

How much is this energy in Me V? (Speed of light= 3 x 10⁸ m/s)

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

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

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

In a nuclear power plant, coolant is a substance :

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

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

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

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

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

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

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

The source of energy of the sun is :

An uncontrolled nuclear chain reaction forms the basis of:

One MeV of nuclear energy is equivalent to:

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

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

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

Which of the following can undergo nuclear fusion reaction?

A nuclear reaction is represented by the following equation:

A nuclear reaction is represented by the equation :

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

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

(c) What does E represent?

(d) State two conditions under which such a reaction takes place.

(e) What type of nuclear bomb is based on similar reactions ?

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

(i) an atom bomb, and

(ii) a hydrogen bomb?

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

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.

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

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

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

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

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

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

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

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

What steps would you suggest to reduce energy consumption?

The major cause of environmental pollution is the use of :

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

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

An energy efficient device for producing light is :