A mixture of $\mathrm{CH}_{4}(\mathrm{~g})$ and $\mathrm{C}_{2} \mathrm{H}_{6}(g)$ has a total pressure of $0.53$ atm. Just enough $\mathrm{O}_{2}(g)$ is added to the mixture to bring about its complete combustion to $\mathrm{CO}_{2}(g)$ and $\mathrm{H}_{2} \mathrm{O}(g) .$ The total pressure of the two product gases is found to be $2.2 \mathrm{~atm}$. Assuming constant volume and temperature, find the mole fraction of $\mathrm{CH}_{4}$ in the mixture.