Propane has been suggested as a cleaner source of fuel for motor vehicles because it generate

lower levels of pollutants compared to gasoline. Consider the combustion of $20kg$ of propane

$(C_3{H}_8)$ with $400kg$ of air and $\{$:$21(mol)\%O_2).$

$($a$)$ Sketch process and include the composition of the exhaust gas.

$($b$)$ Calculate the percentage excess air.

$($c$)$ Evaluate the composition of the exhaust gas in mol percentages on:

$($i$)$ A total basis.

$($ii$)$ A dry basis.