where, d= size (diameter) of a molecule, nV= number of molecules per unit volume, = number density of the molecules, v= average velocity of gas molecules, t= time interval between two successive collisions and V= volume of the molecule. So clearly, mean free path depends on number density of the molecules, volume of the molecule, temperature of the gas (as average velocity of gas molecules depend on temperature of the gas). But mean free path doesn't depend on gas constant R.