Chemistry - GOC Question with Solution | TestHub

Removing H₁ gives a carbanion α to the acid carbonyl :

Removing H₂ gives the carboxylate :

The carboxylate carries the negative charge on oxygen and delocalised over two oxygens by resonance; the carbanion carries it on carbon. The carboxylate is far more stable, so the O-H proton H₂ is much more acidic (carboxylic acid pKa ~ 5 vs α C-H pKa ~ 20).