Question

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

Answer 1

Answer: (A)

$\sqrt{2}:1$

Answer 2

$v_{rms} \propto \frac{1}{\sqrt{M}}$ Ž$\frac{(v_{rms})_{H_{2}}}{(v_{rms})_{He}} = \sqrt{\frac{M_{He}}{M_{H_{2}}}} = \sqrt{\frac{4}{2}} = \frac{\sqrt{2}}{1}$