Which types of resources of energy are coal, petroleum and natural gas?

1. conventional sources
2. non-renewable sources
3. non-conventional sources
4. Both (a) and (b).

Coal is a …………… solid stratified rock of organic and mineral matter.

1. combustible
2. non-combustible
3. renewable
4. None of the above.

Bituminous coal is also known as …………… .

1. coking coal
2. Peat
3. Steam oven
4. Gas stove

Anthracite is ideal for domestic use as it is smokeless and has high …………… value.

1. industrial
2. calorific
3. volatile
4. demand