A $25 \times 10^{-3} \mathrm{~m}^3$ volume cylinder is filled with 1 mol of $\mathrm{O}_2$ gas at room temperature ( 300 K ). The molecular diameter of $\mathrm{O}_2$, and its root mean square speed, are found to be 0.3 nm and 200 $\mathrm{m} / \mathrm{s}$, respectively. What is the average collision rate (per second) for an $\mathrm{O}_2$ molecule?