At an altitude of 30.0 km in the middle of the statosphere, the atmospheric pressure is approximately 0.0130 atm, and the gas density is 3.74 x 10^-23 molecules/ m^3, calculate the following quantities assuming that the air is pure N2(g) whose hard sphere collision radius is 0.19 nm.
(a) the average number of collisions suffered by a single molecule of nitrogen in a second.
(b) the total collision frequency Zbb in 1 / (cm^3 s).
(c) the mean free path in miles