What is the reason of that CBr$4$ is the least volatile one? Does not it has only dispersion force? What makes the huge difference between CH$4$ and CBr$4?$

$($a$)$ Place the following substances in order of increasing volatility: $C{H}_4,CB{r}_4,C{H}_{2}C{l}_2,C{H}_{3}Cl,CHB{r}_3,$ and $C{H}_{2}B{r}_2.($b$)$ How do the boiling points vary through this series? $($c$)$ Explain your answer to part $($b$)$ in terms of intermolecular forces.