Question

The mean free path of molecules of a gas, (radius 'r') is inversely proportional to :

• A. $r^3$
• B. $r^2$
• C. $r$
• D. $\sqrt{r}$

Answer 1

Answer: (B)

$r^2$

Answer 2

Mean free path $\lambda_m = \frac{1}{\sqrt{2} \pi d^2 n}$
where d = diameter of molecule
$\Rightarrow \, \lambda_m \; \propto \frac{1}{r^2}$