Which gas is present both in natural gas and biogas?

Give one advantage of a spherical reflector over a plane reflector.

Name the places of our country where fields of natural gas are found. Why is it called a clean fuel? Give two reasons.

What steps would you suggest to minimise environmental pollution caused by the burning of fossil fuels?

What do you suggest to overcome the problem of "limitation of sources of energy"? Mention any three suggestions for the effective use of energy.

Amount of charcoal produced on the destructive distillation of $1 \, kg$ of wood is about: (in $, kg$)