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