What is the correct relation between boiling points of the following alkyl iodides, where R=methyl, R’=ethyl and R”=propyl?

R”I > R’I > RI

The correct relation between the boiling points of the alkyl iodides is (4) R”I > R’I > RI.

The boiling point of an alkyl halide depends on the size of the alkyl group. The larger the alkyl group, the greater the van der Waals forces between the molecules, and the higher the boiling point. Therefore, R”I, which has the largest alkyl group, will have the highest boiling point, followed by R’I and then RI.