Hydrogen has been used as a rocket fuel would you consider it clear fuel than CNG ? Why or why not ?

Hydrogen has been used as a rocket fuel would you consider it clear fu

1.	Hydrogen has been used as a rocket fuel would you consider it clear fuel than CNG ? Why or why not ?
Answer» Hydrogen is a cleaner fuel than CNG. This is due to the reason that it produces water on burning whereas CNG on burning produces CO2, though much less than that produced when coal or oil is burnt. The increase in concentration of CO2 in the atmosphere increases the temperature of atmosphere.