Which of the following isomers is more volatile: o-nitrophenol or p-nitrophenol?

o-nitrophenol is more volatile than p-nitrophenol. o-nitrophenol involves intramolecular hydrogen bonding and p-nitrophenol involves intermolecular hydrogen bonding. Intermolecular hydrogen bonding leads to association of several molecules of p-nitrophenol which results in a high boiling point and less volatile nature.