Name the places of our country where fields of natural gas are found. Why is it called a clean fuel? Give two reasons.

(N/A) The places where natural gas is found in India are Tripura,Jaisalmer,the off-shore area of Bombay,and the Krishna-Godavari Delta.
Natural gas is called a clean fuel because:
$(i)$ It does not produce harmful gases upon combustion.
$(ii)$ It burns without smoke and does not leave any residue after burning.