Question

If mass of He atom is 4 times that of hydrogen atom then mean velocity of He is

• A. 2 times of H-mean value
• B. 1/2 times of H-mean value
• C. 4 times of H-mean value
• D. Same as H-mean value

Answer 1

Answer: (B)

1/2 times of H-mean value

Answer 2

$v_{av} \propto \frac{1}{\sqrt{M}}$Ž$\frac{v_{He}}{v_{H}} = \sqrt{\frac{M_{H}}{M_{He}}} = \sqrt{\frac{1}{4}} = \frac{1}{2} \Rightarrow v_{He} = \frac{v_{H}}{2}$