Question

justify H2 is a cleaner and better fuel than CNG​

Answer 1

Hydrogen has a higher calorific value than CNG so it is considered as a clean and better fuel

Answer 2

here is the answer of your question

H2 is a cleaner fuel because on combustion of H2 gas it get completely combusted without producing pollution that is why it is also used in rockets as a fuel.. and also on combustion produces more amount of energy

hope it helps you