1. ⇒ (NEET 2020 Phase 1 )

The mean free path for a gas, with molecular diameter d and number density n can be expressed as :

(A) $\frac{1}{\sqrt{2}n\pi d^2}$

(B) $\frac{1}{\sqrt{2}{n}^2\pi d^2}$

(C) $\frac{1}{\sqrt{2}{n}^2{\pi }^2{d}^2}$

(D) $\frac{1}{\sqrt{2}n\pi d}$

2. ⇒ (AIPMT 2014 )

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

(A) r³

(B) r²

(C) r

(D) $\sqrt{r}$