A mixture contains equal masses of H₂, He,O₂and CH₄ at room temperature. The gas having highest molefraction in the mixture is 

${\mathrm{\chi }}_{\left(\mathrm{gas}\right)}=\frac{\mathrm{number} \mathrm{of} \mathrm{moles} \mathrm{of} \mathrm{gas}}{\mathrm{total} \mathrm{number} \mathrm{of} \mathrm{moles}}=\frac{{\mathrm{w}}_{\left(\mathrm{g}\right)}}{{\mathrm{M}}_{\left(\mathrm{g}\right)}}\times \frac{1}{{\mathrm{n}}_{\left(\mathrm{total}\right)}}$

${\mathrm{\chi }}_{\left(\mathrm{gas}\right)}\infty \frac{1}{{\mathrm{M}}_{\left(\mathrm{g}\right)}}$ mass is same and n_(total) is same

order :${\mathrm{\chi }}_{{\mathrm{O}}_2}<{\mathrm{\chi }}_{{\mathrm{CH}}_4}<{\mathrm{\chi }}_{\mathrm{He}}<{\mathrm{\chi }}_{{\mathrm{H}}_2}$