In which one of the following cases mean free path increases 

Options

A. Helium molecules in a container are replaced by oxygen molecules
B. Oxygen molecules in a container replaced by `CO_2` molecules
C. `N_2` molecules in a container are replaced by Helium molecules
D. Helium molecules in a container are replaced by nitrogen molecules

Answer

C

Explanation

`lambda darr` is size of molecules `uarr`.