At constant temperature and pressure,which gas will diffuse first,$H_2$ or $O_2$?

At $400 \ K$,the root mean square $(rms)$ speed of a gas $X$ (molecular weight $= 40$) is equal to the most probable speed of gas $Y$ at $60 \ K$. The molecular weight of the gas $Y$ is:

Explain the relationship between different types of molecular speeds.

The temperature at which oxygen molecules have the same root mean square speed as helium atoms have at $300 \ K$ is (Atomic masses: $He = 4 \ u$,$O = 16 \ u$) (in $K$)

The $RMS$ velocity $(u_{rms})$ of one mole of an ideal gas was measured at different temperatures and the following graph is obtained. What is the slope $(m)$ of the straight line?
($x$-axis $= T$ $(K)$; $y$-axis $= (u_{rms})^2$; $M =$ molar mass; $R =$ gas constant)

What would be the ratio of the root mean square velocity of hydrogen gas at $50 \ K$ and that of oxygen at $800 \ K$?