A combustion chamber is used to burn a fuel mixture consisting of methane and ethane. The fuel enters the chamber at a temperature

of $25C$ and a pressure of $1$atm. Dry air enters the chamber at a temperature of $200C$ and a pressure of $1$atm. Excess air is used for

combustion. Assume the air to be $21\mathrm{.}0$mole$\%O_2$ and the balance $N_2.$ The flue gas exits at a temperature of $800C$ and a pressure of $1$

atm. Analysis of the flue gas has the following composition in mole percent: $1\mathrm{.}08\%CO,6\mathrm{.}57\%C{O}_2,14\mathrm{.}03\%H_{2}O,5\mathrm{.}29\%O_2$ and the

balance $N_2.$

What is the mole percent of ethane in the fuel mixture?

$\%$

What is the percentage by which dry air is fed in excess?

i

$\%$