Question

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

• A. 64
• B. 32
• C. 4
• D. 8

Answer 1

The correct option is A 64

According to Graham's law of diffusion, the rates of diffusion of gases are inversely proportional to the square root of their molecular weights.

$\frac{r_{C{H}_4}}{r_x}=\sqrt{\frac{M_{C{H}_4}}{M_x}}$

Substitute values in the above expression.

$\frac{{}^{r}C{H}_4}{r_x}=2=\sqrt{\frac{M_x}{16}}$

Thus the molecular weight is 64 $g/mol$.