Question

Which of the following gases has maximum rms speed at a given temperature?
(a) hydrogen
(b) nitrogen
(c) oxygen
(d) carbon dioxide.

Answer 1

The rms speed of a gas is given by ​$\sqrt{\frac{3RT}{M_o}}$.
Since hydrogen has the lowest M_o compared to other molecules, it will have the highest rms speed.
Thus, (a) is the correct answer.