Two gaseous molecules `A` and `B` are traveling towards each other. Let the mean free path of the molecule be `sigma` and `Z` be the collision number with other molecules at pressure `1 atm`. Answer the following questions
If `Z` is the total number of collisions which a gas molecule registers with others per unit time under particular conditions, then the collision frequency of the gas containing `N` molecules per unit volume is

Options

A. `(Z)/(N)`
B. `NZ`
C. `2NZ`
D. `(NZ)/(2)`

Explanation

Collision frequency is proportional to `N`. Therefore,
`Z=(NZ)/(2)`