Rank the following compounds in order of increasing melting point, putting the compound with the least melting point first.

Question

Quizplus · Accepted Answer

We can use the intermolecular forces to determine the relative melting points of the compounds. 
Compound I contains only dispersion forces, while compound II contains hydrogen bonding and compound III contains dipole-dipole interactions. 
Since hydrogen bonding is the strongest intermolecular force, compound II will have the highest melting point. 
Following that, compound I will have a lower melting point than compound III, as dipole-dipole interactions are stronger than dispersion forces. 
Therefore, the correct order is I < II < III, which corresponds to answer choice C.

Rank the Following Compounds in Order of Increasing Melting Point