NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy

The Class 10 NCERT Solutions for Science Chapter 14 Sources of Energy includes all the intext and exercise questions. Class 10 Science Chapter 14 Sources of Energy NCERT questions and answers help students to clear their doubts and to obtain good marks in Class 10 board exam. All the solutions provided in this article are strictly based on the CBSE syllabus and curriculum.

Class 10 Science Chapter 14 NCERT Questions and Answers

Class 10 Science Chapter 14 Sources of Energy NCERT Questions and Answers are prepared by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 10 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc.

NCERT Solutions for Class 10 Science Chapter 14 Intext Questions

Intext Question (Page No. 243)

Question 1: What is a good source of energy?

Answer: A good source of energy should have the following qualities:

It should be easily available.
It should do a large amount of work (or produce large amount of heat) per unit volume/mass.
It should be easy to store and transport.
It should be economical.
It should cause less environmental pollution.

Question 2: What is a good fuel?

Answer: A good fuel is one which has the following properties :

It should be fairly cheap.
It should be easily available.
Its ignition temperature should be well above normal temperature.
It should be conveniently handled and transported.
It should not produce any poisonous material during burning.
Its combustion rate should be steady and controllable.
It should not leave any residue or ash after burning.
A good fuel should have high calorific value so that higher amount of heat may be obtained by burning a little fuel.

Question 3: If you could use any source of energy for heating your food, which one would you use and why?

Answer: We shall use LPG/CNG gas or electricity for heating our food because these are efficient ways of supplying energy. Thermal efficiency of the energy source is large, there is less pollution and the source can be used easily.

Intext Question (Page No. 248)

Question 1: What are the disadvantages of fossil fuels?

Answer: Following are the disadvantages of fossil fuels:

Fossil fuels like coal and petroleum results in air pollution as there is release of huge amount of pollutants.
Gases such as carbon dioxide is released when a fossil fuel is burnt, which causes global warming.
Soil fertility and potable water is affected by the oxides of carbon, nitrogen, sulphur, etc. that are released from fossil fuels.

Question 2: Why are we looking at alternate sources of energy?

Answer: The reason why we are looking at alternate sources of energy is because the fossil fuels are non-renewable sources of energy, i.e. they are not available in large quantities and cannot be replenished. Fossil fuels will get exhausted if their consumption is not controlled. Therefore, it is better to switch to alternate source of energy.

Question 3: How has the traditional use of wind and water energy been modified for our convenience?

Answer: To use energy of flowing water large dams are built in hilly regions to store huge amount of water at a height. The stored water from high level in dam is carried through pipes to the turbine at the bottom of the dam and runs hydropower plant. Similarly, the wind energy is used to generate electricity. For the same purpose, the rotatory motion of windmill is used to tum the turbine of the electric generator.

Intext Question (Page No. 253)

Question 1: What kind of mirror – concave, convex or plain – would be best suited for use in a solar cooker? Why?

Answer: For a solar cooker the heat source is sunlight for heating and cooking. The reason why a mirror is used is to reflect and focus the sunlight at one point. So a concave mirror can be used in a solar cooker, as it focuses all the sunlight at one point resulting in increase in temperature, thereby heating and cooking the food.

Question 2: What are the limitations of the energy that can be obtained from the oceans?

Answer: The energy from the oceans can be obtained mainly in three forms. These are
(i) tidal energy
(ii) wave energy and
(iii) ocean thermal energy

Limitations of Tidal Energy:
(i) There are very few sites around the world which are suitable for building tidal dams.
(ii) The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.

Limitations of wave energy: The movement of ocean waves is associated with kinetic energy. Such sites in the world are limited where the waves strike the shore lines with sufficient power.

Limitations of ocean thermal energy: NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy to convert ocean thermal energy into electricity, a temperature difference of 20°C (or more) between the surface water of ocean and deeper water is needed for operating OTEC power plants. This involves high cost

Question 3: What is geothermal energy?

Answer: Energy stored as heat in certain regions of the earth (called hot spots) is called geothermal energy. Hot spots are the locations below earth’s crust where upward moving magma gets collected due to geological changes. When underground water comes in contact with the hot spots, steam is generated. This steam is utilised to generate electricity using pipes and turbines. Sometimes hot water from the hot spot finds outlet at the surface. Such outlets are called hot springs.

Question 4: What are the advantages of nuclear energy?

Answer: The advantages of nuclear energy are as follows:

Large amount of energy is produced per unit mass.
It does not produce smoke. It is a clean energy.
Fission of one atom of uranium produces 10 million times the energy released by burning of one atom of carbon.
Fusion of four hydrogen atoms produces huge amount of energy.

Intext Question (Page No. 253)

Question 1: Can any source of energy be pollution-free? Why or why not?

Answer: No source of energy can be pollution-free. It is considered that solar cells are pollution-free. However, even their making causes environmental damage indirectly. Also, in the case of nuclear energy, there is no waste produced after the fusion reactions. However, it is not totally pollution-free. To start the fusion reactions, approximately 107 K temperature is required, which is provided by fission reactions. The wastes released from fission reactions are very hazardous. Hence, no source of energy is pollution-free.

Question 2: Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?

Answer: Hydrogen is cleaner fuel than CNG. This is because the burning of hydrogen produces only water, which is totally harmless. On the other hand, burning of CNG produces carbon dioxide gas and water. The carbon dioxide can produce greenhouse effect in the atmosphere and lead to the excessive heating of the environment in long run.

Intext Question (Page No. 254)

Question 1: Name two energy sources that you would consider to be renewable. Give reasons for your choices.

Answer: Solar energy, wind energy, ocean energy etc., are renewable sources of energy due to the following reasons:

These forms of energy are available in plenty in our natural environment in the form of continuous currents of energy.
These energy sources will not be depleted because their supply is large and extraction of usable energy from these sources is negligible.

Question 2: Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.

Answer: Coal and petroleum are two exhaustible sources of energy. These fuels were formed over millions of years ago and there are only limited reserves. If we continue to use them as at present, these reserves will be exhausted very soon.

NCERT Solutions for Class 10 Science Chapter 14 Exercise Questions

Question 1: A solar water heater cannot be used to get hot water on
(a) a sunny day
(b) a cloudy day
(c) a hot day
(d) a windy day

Answer: (b) a cloudy day

For solar water heater to work, sunlight is required and on a cloudy day, the sunlight is not available.

Question 2: Which of the following is not an example of a biomass energy source?
(a) Wood
(b) Gobar gas
(c) Nuclear energy
(d) Coal

Answer: (c) Nuclear energy

Nuclear energy is not an example of a biomass energy source. The biomass energy sources are wood, coal, cow dung, gobar-gas etc.

Question 3: Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?

(a) Geothermal energy
(b) Wind energy
(c) Nuclear energy
(d) Biomass

Answer: (c) nuclear energy

Question 4: Compare and contrast fossil fuels and the Sun as direct sources of energy.

Answer:

Fossil fuels	Sun
(i) Non-renewable source of energy.	(i) Renewable source of energy.
(ii) Cause a lot of air pollution.	(ii) Pollution-free, doesn’t cause any pollution.
(iii) They will exhaust in future.	(iii) It is a non-exhaustible source.
(iv) Energy can be tapped throughout the year.	(iv) Energy cannot be tapped during night and cloudy and rainy days.

Question 5: Compare and contrast biomass and hydroelectricity as sources of energy.

Answer:

Biomass	Hydroelectricity
(i) Renewable source of energy.	(i) Renewable source of energy.
(ii) Biomass plants can be installed at any place to produce biomass as energy source.	(ii) Plants can be installed only at the places where dams can be constructed.
(iii) To collect waste materials is a tough and costly process.	(iii) Once the plants start to work, it is not difficult to collect water.

Question 6: What are the limitations of extracting energy from—
(a) the wind?
(b) waves?
(c) tides?

Answer: (a) Limitations of wind energy

(i) Wind energy farms cannot be established everywhere. The wind energy farms can be established only at those places, where wind blows for most part of the year.

(ii) The wind required for generating electricity should be strong and steady to maintain the desired level of generation. The minimum wind speed necessary for satisfactory working of the wind generator is about 15 km/h. This is not always so.

(iii) The wind energy farms require a large area of land.

(iv) The setting up of wind energy farms is very expensive.

(b) Limitations of wave energy: The harnessing of sea-waves energy would be a viable proposition only at those places where sea-waves are very strong. This has constraints of time and location.

(c) Limitations of tidal energy:

(i) There are very few sites around the world which are suitable for building tidal dams.

(ii) The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.

Question 7: On what basis would you classify energy sources as
(a) renewable and nonrenewable?
(b) exhaustible and inexhaustible?
Are the options given in (a) and (b) the same?

Answer: (a) Renewable and non-renewable:
Renewable energy sources are those which replenish on their own and are easily available in nature. Like solar energy, tidal energy, wind energy, bio-mass.

Non-renewable energy sources are those which do not replenish on their own and have limited availability in nature. Like fossil fuels which includes petroleum, coal and natural gas.

(b) Exhaustible and inexhaustible:
Exhaustible sources of energy are those which deplete after few hundred years. Like coal and petroleum.

Inexhaustible sources of energy are those which do not deplete and are available in abundant quantity. Like solar and wind energy.

Question 8: What are the qualities of an ideal source of energy?

Answer: Followings are the qualities of an ideal source of energy:

It should do a large amount of work per unit volume or mass.
Which would be easily accessible.
Which would be easy to store and transport.
be economical.

Question 9: What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?

Answer: The advantages of the solar cooker are:

The cost of making such a cooker is very less.
The food never gets burnt in this type of cooker and stays hot.

The disadvantages of the solar cooker are:

This type of cooker cannot be used for frying or preparing chapatis.
This device cannot be used at night for preparing food.

In a colder climate where there is not enough sunshine all year, the solar cooker would have very limited utility.

Question 10: What are the environmental consequences of the increasing demand for energy? What steps would you suggest to reduce energy consumption?

Answer: Some of the environmental consequences of the increasing demand for energy are the following:

The combustion of fossil fuels is producing acid rain and damaging plants (crops), soil and aquatic life.
The burning of fossil fuels is increasing the amount of greenhouse gas carbon-dioxide in the atmosphere. It has also affected the rainfall.
The cutting down of trees from the forest for obtaining fire-wood is causing soil erosion and destroying wild life.
The construction of hydro-power plants is disturbing ecological balance.
Nuclear power plants are increasing radioactivity in the environment.

The following steps can be taken to reduce energy consumption:

Switch off lights, fans, TV. and other such electrical appliances when not needed, to save electricity.
Use energy efficient electrical appliances to save electricity. This can be done by using compact fluorescent lamps (CFL) and tube lights in place of conventional filament- type electric bulbs.
Good quality stoves should be used to burn fuels like kerosene and LPG so as to obtain maximum heat.
Pressure cookers should be used for cooking food to save fuel.
Solar cookers should be used to cook food whenever possible and solar water heaters should be used to get hot water.
The use of biogas as fuel should be encouraged in rural areas.
Bicycles should be used for short distances to save fuel like petrol which is used in cars, scooters and motorcycles.

Topics covered under Class 10 Science Chapter 14 Sources of Energy

Below we have listed the topics discussed in NCERT Solutions for Class 10 Science Chapter 14. The list gives you a quick look at the different topics and subtopics of this chapter.

Section in NCERT Book	Topics Discussed
14.1	What is a Good Source of Energy?
14.2	Conventional Sources of Energy
14.3	Alternative or Non-Conventional Sources of Energy
14.4	Environmental Consequences
14.5	How Long will an Energy Sources last us?

NCERT Solutions for Class 10 Science Chapter 14 – A Brief Discussion

Chapter Overview: This chapter explains the different sources of energy such as conventional and non-conventional sources of energy. Conventional sources of energy include fossil fuels, thermal power plants, hydro power plants whereas non-conventional energy sources include wind energy, solar energy, geothermal energy, nuclear energy etc.