Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

The compound is benzene-1,3-diol (resorcinol). The two O-H protons exchange instantly. In addition, resorcinol behaves partly like a tautomeric diketone : the ring hydrogen at C-2, lying between the two $\mathrm{OH}$ groups, is alpha to both carbonyls in the diketo tautomer and exchanges with deuterium under $\mathrm{O}{\mathrm{D}}^{-}/{\mathrm{D}}_2\mathrm{O}$. Total = 2 (O-H) + 1 (ring C-H) = 3.