Since joule is a very small unit of heat energy, so the calorific value is usually expressed as kilojoules per gram (kJ/g). hydrogen gas has the highest calorific value of 150 kilojoules per gram. Thus, because of its high calorific value, hydrogen is an extremely good fuel. Most of the common fuels are the compounds of hydrogen and carbon called 'hydrocarbons'. LPG has a higher percentage of hydrogen than coal, so “PG has a higher calorific value than coal.1. The calorific value of fuels is usually expressed asa. J/gmb. gmc. KJ/gmd. None of these2. Which element has the highest calorific valuea. Methaneb. Coalc. Hydrogen gasd. None of these3. Calorific value of hydrogen gas isa. 150 KJ/gb. 55 KJ/gc. 50 KJ/gd. None of these4. The compounds of hydrogen and carbon are calleda. Hydrocarbonsb. Carbonatesc. Hydroxidesd. None of these5. Which of the following has higher percentage of hydrogen?a. Coalb. LPGc. Woodd. Cow dung cakes