Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their
1) Formation of carboxylate ion
2) More extensive association of carboxylic acid via van der Waals force of attraction
3) Formation of intermolecular H-bonding
4) Formation of intramolecular H-bonding
3) Formation of intermolecular H-bonding