The following reaction takes place in a system consisting of \(3 \mathrm{~mol} \mathrm{CH}_{4}, 5 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}\), \(1 \mathrm{~mol} \mathrm{CO}\) and \(4 \mathrm{~mol} \mathrm{H}_{2}\) initially:

\[ \mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightarrow \mathrm{CO}(\mathrm{g})+4 \mathrm{H}_{2}(\mathrm{~g}) \]

Express the composition of the mixture in terms of mole fraction as a function of extent of reaction.