Question

The rate of diffusion of methane at a given temperature is twice that of gas $X$ the molecular weight of $X$ is:

• A. $32$
• B. $16$
• C. $8$
• D. $64$

Answer 1

The correct option is D $64$

$rate\propto \frac{1}{\sqrt{M}}\therefore \frac{r_{{CH}_4}}{r_X}=\sqrt{\frac{M_X}{M_{{CH}_4}}}⟹\frac{2}{1}=\sqrt{\frac{M_X}{16}}⟹M_X=64g{mol}^{-1}$