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