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

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Professor PC Thomas Classes · Answer

(b) : Mean free path, $\lambda=\frac{1}{\sqrt{2} n \pi d^{2}}$\ where $n$ is the number density and $d$ is the diameter of the molecule.\ As $d=2 r, 	herefore \lambda=\frac{1}{4 \sqrt{2} n \pi r^{2}} \quad$ or $\quad \lambda \propto \frac{1}{r^{2}}$