By what factor does the average velocity of a gaseous molecule increase when the temperature (in Kelvin) is doubled?

The following graph is obtained for a gas at different temperatures $T_1$,$T_2$,$T_3$. What is the correct order of temperature? ($x$-axis $=$ velocity; $y$-axis $=$ number of molecules)

If the most probable speed of $CO_2$ at $27^{\circ} C$ is $400 \ ms^{-1}$,the root mean square velocity of $CO_2$ at the same temperature in $ms^{-1}$ is approximately:

Let $(C_{rms})_{H_2}$ be the r.m.s. speed of $H_2$ at $150 \ K$. At what temperature will the most probable speed of helium $[(C_{mp})_{He}]$ be half of $(C_{rms})_{H_2}$ (in $K$)?

For a gaseous state,if the most probable speed is denoted by $C^*$,average speed by $\overline{C}$,and root mean square speed by $C$,then for a large number of molecules,the ratio of these speeds is:

The distribution of molecular velocities of three gases of molar masses $M_1$,$M_2$,and $M_3$ at $T(K)$ are shown below. The correct relation of their molar masses is: