(a) CNG-compressed natural gas. It is a type of natural gas which is a non- renewable source of energy as it takes thousands of years to get replenished. Thus CNG is a non-renewable source while hydrogen is a renewable source.
(b) Hydrogen is a much cleaner fuel than CNG because-
• There is no hydrocarbon emission from hydrogen while CNG produces a lot of hydrocarbon emission which can cause pollution.
