Q. At a given temperature the ratio of $r.m.s.$ velocities of hydrogen molecule and helium atom will be
A) $\sqrt{2}\ :1$
B) $1\ :\sqrt{2}$
C) $1\ :2$
D) $2\ :1$
Explanation
(a) $v_{rms} \propto \frac{1}{\sqrt{M}} \Rightarrow \frac{\left( v_{rms} \right)_{H_{2}}}{\left( v_{rms} \right)_{He}} = \sqrt{\frac{M_{He}}{M_{H_{2}}}} = \sqrt{\frac{4}{2}} = \frac{\sqrt{2}}{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.