Question

The average velocity of molecules of a gas of molecular mass $M$ at temperature $T$ is

• A. $0$
• B. $\sqrt{\frac{3RT}{M}}$
• C. $\sqrt{\frac{8RT}{\pi M}}$
• D. $\sqrt{\frac{2RT}{M}}$

Answer 1

The correct option is A $0$

In Kinetic Theory of Gas, we assume speed of a gas molecule to be constant at constant temperature.
If it collides with walls of the container or with other molecules, then its speed remain constant and direction reverses as collision is assumed to be elastic.


Therefore, average velocity become zero as ${\overrightarrow{v}}_{av}=\frac{{\overrightarrow{v}}_f+{\overrightarrow{v}}_i}{2}=\frac{-v+v}{2}=0$.
Hence, average velocity of molecules of a gas is zero.