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 (1) and (2).

…………… coal has …………… per cent of carbon content and is the most preferred variety of coal.

1. Lignite, 40
2. Peat, 50
3. Anthracite, 90
4. Bituminous, 80

Assertion (A): Natural gas is an eco-friendly fuel.

Reason (R): It is lighter than air and tends to dissipate in case of leakage.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Anthracite is ideal for domestic use as it is …………….

1. smokeless
2. high calorific value
3. high carbon content
4. All of them.