Question

The ratio of the rate of diffusion of helium and methane under the identical conditions of pressure and temperature will be:

• A. 4
• B. 2
• C. 1
• D. 0.5

Answer 1

The correct option is B 2

From Graham's law of diffusion at constant pressure,
$\text{Rate of diffusion for a gas}\left(r\right)\propto \frac{1}{\sqrt{M}}$
where, $M$ is the molar mass of the gas

$\therefore \frac{r_{He}}{r_{C{H}_4}}=\sqrt{\frac{M_{C{H}_4}}{M_{He}}}=\sqrt{\frac{16}{4}}=2$