Amixture of air and methane is formed in the inlet manifold of a natural gas-fueled internal combustion engine. the mole fraction of the methane is 15 percent. this engine is operated at 3000 rpm and has a 5-l displacement. determine the mass flow rate of this mixture in the manifold where the pressure and temperature are 80 kpa and 20oc. ( 6.65 kg/min)