Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

This compound has$\mathrm{\alpha }$-H on saturated$\mathrm{\alpha }$-carbon atom so it can show tautomerism.

In rest other compounds there is no$\mathrm{\alpha }$-H-atom on saturated$\mathrm{\alpha }$-Carbon so no tautomerism is possible in them.