The mean free path for a gas, with molecular diameter d and number density n can be expressed as : [NEET 2020]

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

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

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

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