Density ratio of \[O_{2} and H_{2}\]  is 16:1. The ratio of their r.m.s. velocities will be
a) 4 : 1
b) 1 : 16
c) 1 : 4
d) 16 : 1

Answer: c
Explanation: \[\frac{U_{1}}{U_{2}}= \sqrt{\frac{d_{2}}{d_{1}}} = \sqrt{\frac{1}{16}} = 1:4\]