The ratio of average speed of an oxygen molecule to the RMS speed of a nitrogen molecule at the same temperature is :

Question

$(a)\;(\large\frac{3\pi}{7})^{\large\frac{1}{2}}\qquad(b)\;(\large\frac{7}{3\pi})^{\large\frac{1}{2}}\qquad(c)\;(\large\frac{3}{7\pi})^{\large\frac{1}{2}}\qquad(d)\;(\large\frac{7\pi}{3})^{\large\frac{1}{2}}$