Question

The Mean Free Path $l$  for a gas molecule depends upon diameter, $d$ of the molecule as

(1) $l\propto{1\over d}$

(2) $l\propto{1\over d^2}$

(3) $l\propto d$

(4) $l\propto d^2$

Answer 1

Ans: (2) $l\propto{1\over d^2}$

Sol. Mean free path $(l)$

$l={1\over\sqrt2n\pi d^2}$

$l\propto{1\over d^2}$