Question

In comparison to molecules that interact by London dispersion forces only, the melting point of similar-sized molecules forming hydrogen bonds would most likely be?

Answer 1

Van der Waals' forces of attraction (also known as London dispersion forces) are the residual attractive or repulsive forces between molecules or atomic groups that do not arise from a covalent bond, or electrostatic interaction of ions or of ionic groups with one another or with neutral molecules.
Hydrogen bond is an attraction between a slightly positive hydrogen on one molecule and a slightly negative atom on another molecule.

Considering the fact that London dispersion forces are the weakest bounds, melting point of the substances with this type of intermolecular interaction will be less than that of with hydrogen bounds.