If $\mathrm{n}$ is the number density and $\mathrm{d}$ is the diameter of the molecule, then the average distance covered by a molecule between two successive collisions (i.e. mean free path) is represented by :

• A

  $\sqrt{2} \mathrm{n} \pi \mathrm{d}^2$
• B

  $\frac{1}{\sqrt{2 n \pi d^2}}$
• Correct answer
  C

  $\frac{1}{\sqrt{2} n \pi d^2}$
• D

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

Hence, the correct answer is option: 'C'.