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: $0\mathrm{.}97\%CO,6\mathrm{.}86\%C{O}_2,$

$14\mathrm{.}35\%H_{2}O,4\mathrm{.}88\%O_2$ 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?

$\%$