In the adjoining figure,various isothermals are shown for a real gas. Then

$A$ molecule is travelling in air at $300 \, K$ and $1 \, atm$, and the radius of the molecule is $0.6 \times 10^{-10} \, m$. Calculate the approximate mean free path of the molecule. (The number density is $2.44 \times 10^{25} \, \text{molecules}/m^3$)

Every real gas behaves as an ideal gas:

If the radius of an $O_{2}$ molecule is $40 \; \mathring{A}$,$T = 27^{\circ}C$,and $P = 1 \; \text{atm}$,find the relaxation time.

The value of critical temperature in terms of van der Waals' constants $a$ and $b$ is given by

Calculate the mean free path and relaxation time for a gas with a mean speed $\langle v \rangle = 485 \ m/s$. Assume standard conditions $(STP)$ where the number density $n \approx 2.7 \times 10^{25} \ m^{-3}$ and molecular diameter $d = 2 \ \mathring{A}$.