How does the $rms$ velocity of an ideal gas vary with density at constant pressure?

The ratio of $r.m.s.$ velocities of oxygen and hydrogen at a given temperature is:

For a particular ideal gas,which of the following graphs represents the variation of the mean squared velocity of the gas molecules with temperature?

$A$ gas is allowed to expand isothermally. The root mean square velocity of the molecules

Three closed vessels $A, B$ and $C$ are at the same temperature $T$ and contain gases. Vessel $A$ contains only $O_2$,vessel $B$ contains only $N_2$,and vessel $C$ contains a mixture of equal quantities of $O_2$ and $N_2$. If the rms speed of $O_2$ molecules in vessel $A$ is $v_1$ and that of $N_2$ molecules in vessel $B$ is $v_2$,then the rms speed of $O_2$ molecules in vessel $C$ is:

The rms speed of an oxygen molecule in a vessel at a particular temperature is $\left(1+\frac{5}{x}\right)^{\frac{1}{2}} v$,where $v$ is the average speed of the molecule. The value of $x$ will be: (Take $\pi=\frac{22}{7}$)