Question

The ratio of rates of diffusion of two gases is 6:4. Calculate the ratio of their Molecular Weights.

• A. 9:4
• B. 6:4
• C. 4:9
• D. 8:3

Answer 1

The correct option is C 4:9

Let the rates of diffusion of one gas be $r_1$ and another gas to be $r_2$ and their Molecular weights be
$M_1$ and $M_2$ respectively
According to Graham’s Law of diffusion
$\frac{r_1}{r_2}=\sqrt{\frac{M_2}{M_1}}or,\frac{6}{4}=\sqrt{\frac{M_2}{M_1}}$
or, $\frac{36}{16}=\frac{M_2}{M_1}$
$\therefore \frac{M_1}{M_2}=\frac{4}{9}$
or, $M_1:M_2=4:9$