Find vapor density of mixture having 64% by mass of ${\mathrm{CH}}_4$, 32% by mass of ${\mathrm{O}}_2$, and remaining ${\mathrm{H}}_2$ :

As we know that,

$M=\frac{64+32+4}{\frac{64}{16}+\frac{32}{32}+\frac{4}{2}};V.D.=\frac{M}{2}$

Thus, the vapor density of the mixture having 64% by mass of ${\mathrm{CH}}_4$, 32% by mass of ${\mathrm{O}}_2$, and the remaining ${\mathrm{H}}_2$ is 7.14