Question

How are fuels classified on the basis of their physical state? Give two examples of each.

Answer 1

We know that matter can exist in three states $-$ solid, liquid and gas.
On this basis, fuels can be classified as follows:
Solid fuels: Examples: Wood, coal, cattle-dung cakes, bagasse (sugarcane from which juice has been extracted), etc.
Liquid fuels: Examples: Kerosene, liquefied petroleum gas (LPG), fuel oil, petrol, diesel, etc.
Gaseous fuels: Examples: Natural gas, coal gas, water gas, producer gas, biogas, acetylene, etc.