o-Hydroxybenzaldehyde is a liquid at room temperature while p-hydroxybenzaldehyde is a high milting solid because of

Explanation

Interamolecular hydrogen bonding is present in the o-hydroxyzaldehyde and it exists as single molecules. On the other hand, there is association in the molecules of p-hydroxybenzaldehyde because of inter molecular hydrogen bonding. As a result, the molecules get aggregated resulting in a high melting solid. But due to lack of association, o-hydroxybezaldehyde is a liquid at room temperature

Intermolecular hydrogen bonding (no association in the molecules)

Intermolecular hydrogen bonding (Association is present in the molecules)