Among the following,identify the gas which has the greatest average speed of its molecules?

$RMS$ velocity of one mole of an ideal gas was measured at different temperatures. $A$ graph of $(u_{rms})^2$ (on y-axis) and $T(K)$ (on x-axis) gave a straight line passing through the origin and its slope is $249 \ m^2 \ s^{-2} \ K^{-1}$. What is the molar mass (in $kg \ mol^{-1}$) of the ideal gas? $(R=8.3 \ J \ mol^{-1} \ K^{-1})$

At what temperature will the average speed of $CH_4$ molecules have the same value as $O_2$ has at $300 \ K$ ........... $K$

The relationship among most probable velocity,average velocity,and root mean square velocity is respectively:

At $T(K)$, the root mean square (rms) velocity of argon (molar mass $40 \ g \ mol^{-1}$) is $20 \ ms^{-1}$. The average kinetic energy of the same gas at $T(K)$ (in $J \ mol^{-1}$) is:

At what temperature and $1 \ atm$ pressure will the root mean square speed of $N_2$ gas be equal to the root mean square speed of $CO_2$ gas at $STP$?