Solution:
Concept- Calorific value refers to the amount of heat produced by a unit volume of a substance through complete combustion.Now, how good a fuel is based on its calorific value. Thus, higher the calorific value, higher is the efficiency of fuel.
The Calorific values of some fuels are:
Petrol: 48,000 kJ/kg
Coke: 31,000 kJ/kg
Natural gas: 43,000 kJ/kg
Kerosene: 46,200 kJ/kg
LPG: 55,000 kJ/kg
Hydrogen: 1,50,000 kJ/kg
Therefore, hydrogen gas has the highest calorific value. It means on burning 1 g of hydrogen gas, more heat is produced when compared to burning 1 g of methane or wood or petrol.
Thus, the fuel with the highest calorific value is hydrogen gas.
Hence, the correct answer is 2.
