A gaseous fuel with 80 percent CH4, 15 percent N2, and 5 percent O2 (on a mole

Question:

A gaseous fuel with 80 percent CH4, 15 percent N2, and 5 percent O2 (on a mole basis) is burned to completion with 120 percent theoretical air that enters the combustion chamber at 30oC, 100 kPa, and 60 percent relative humidity. Determine
(a) The air-fuel ratio
(b) The volume flow rate of air required to burn fuel at a rate of 2 kg/min.