# Sources of Energy

## Class 10 NCERT Science

### NCERT

1   What is a good source of energy?

##### Solution :

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.

2   What is a good fuel?

##### Solution :

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

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

##### Solution :

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.

4   What are the disadvantages of fossil fuels?

##### Solution :

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 produces gases such as carbon dioxide that causes global warming.

5   Why are we looking at alternate sources of energy?

##### Solution :

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.