The $rms$ velocity of a gas depends upon

The $RMS$ velocity of $CO$ gas molecules at $27^{\circ} C$ is approximately $1000 \ m / s$. For molecules at $600 \ K$, the $RMS$ velocity is approximately (in $m / s$)

Amongst the following, which should have the highest $rms$ speed at the same temperature?

The gas that has the slowest rate of diffusion among $O_2$,$H_2$,$CO_2$ and $CH_4$ is

The ratio of the root mean square velocity of $H_2$ at $50 \ K$ to that of $O_2$ at $800 \ K$ is .......

The given figure shows the Maxwell distribution of molecular speeds of a gas at three different temperatures $T_1$, $T_2$ and $T_3$. The correct order of temperature is