The mean free path of gas molecules is proportional to n^th power of diameter of molecules. Here n is

CONCEPT:

Mean Free Path (λ): 

• The distance travelled by a gas molecule between two successive collisions is known as a free path.
  
• During two successive collisions, a molecule of gas moves in a straight line with constant velocity, and the mean free path of a gas molecule is given by
  

Where n = number of molecules per unit volume and d = diameter of a molecule

EXPLANATION:

• The mean free path of a gas molecule is given by

⇒ λ ∝ d^-2