(Solved): can you please explain how to do this?  Rank the following compounds in order of their boiling ...

Rank the following compounds in order of their boiling points, with the highest boiling point having the highest number and the lowest boiling point having the number 1 . \[ \mathrm{CH}_{3} \mathrm{I} \] \[ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{I} \] \[ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{I} \] \[ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \text { I } \] \[ \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{I} \]