Previous Year NEET Question- Kinetic Theory L-10

Question: $ The mean free path I for a gas molecule depends upon diameter, $d$ of the molecule as [NEET (Oct.) 2020]#

A) $I \propto \frac{1}{d^2}$

B) $1 \propto d$

C) $1 \propto d^2$

D) $1 \propto \frac{1}{d}$

Answer: $I \propto \frac{1}{d^2}$#

Solution:#

The mean free path / for a gas molecule is given as $$ I=\frac{1}{\sqrt{2} \pi n d^2} \Rightarrow I \propto \frac{1}{d^2} $$ where, $d$ = diameter of molecule of gas.