NCERT Solutions for Class 10 Science Chapter 14 Sources of Energy

Ans : A good source of energy fulfils the following criteria:
(I) It produces a lot of heat per unit mass.
(II) It does a huge amount of work per unit mass.
(III) It is easily accessible.
(IV) It is easy to store and transport.
(V) It is economical.
(VI) It produces less amount of smoke. 

Ans : A good fuel produces a huge amount of heat on burning, does not produce a lot of smoke, and is easily available. 

Ans : Natural gas can be used for heating and cooking food because it is a clean source of energy. It does not produce huge amount of smoke on burning. Although it is highly inflammable, it is easy to use, transport, and it produces a huge amount of heat on burning. 

Ans : The disadvantages of fossil fuels are as follows:
(a) Burning of coal and petroleum produces a lot of pollutants causing air pollution.
(b) Fossil fuels release oxides of carbon, nitrogen, sulphur, etc. that cause acid rain, which affects the soil fertility and potable water.
(c) Burning of fossil fuels produce gases such as carbon dioxide that causes global warming. 

Ans : Fossil fuels, which have been traditionally used by human beings as an energy sources, are non- renewable sources of energy. These sources of energy are limited and cannot replenish on their own. They are being consumed at a large rate. If this rate of consumption continues, then the fossil fuels would be exhausted from the Earth.
Therefore, we have to conserve the energy sources. Hence, we should look for alternate sources of energy.