Nitrogen Gas Is Heated by a Pulsed Laser to 50°000

Nitrogen gas is heated by a pulsed laser to 50°000 K. If the diameter of the nitrogen atoms is assumed to be 1.0 * 10-10 m, and the pressure is 1.0 atm, what is the mean free path?

A) 1.5 *10-4 m
B) 1.5 * 10-7 m
C) 1.5 * 10-10 m
D) 1.5 * 10-14 m
E) 1.5 * 10-2 m