What is the single-particle collisional frequency (for diatomic Nitrogen)at sea level, with 341 and 1.0 atm? The corresponding single-particle collisional frequency is reported as 10^10 s^-1. Know the answer is 7x10^9 collisions/s but do not know formula used (with collsions frequency (s^-1)instead of collisional cross section in nanometers).