Which compound has the highest boiling point? HF, HI, HBr, HCl, or F2?

HF

Explanation:

This concept can be understood from the knowledge of Intermolecular forces of attraction.

Intermolecular bonds are Van der Waals forces which are weak forces of attraction joining non-polar and polar molecules together. They exist in the form of London Dispersion Forces and Dipole-dipole attraction.

An example of Dipole-dipole attraction is the hydrogen bond which is a unique dipole-dipole attraction between polar molecules in which a hydrogen atom is directly joined to a highly electronegative atom such as fluorine, oxygen, or nitrogen).

Molecules that possess the characteristics of hydrogen bonding have a higher boiling point. In the given question, only HF undergo hydrogen bond due to the electronegative effect of the fluorine element.

F2 occurs as a weak London dispersion force and it occurs between non-polar molecules.