Chemistry - GOC Question with Solution | TestHub

A compound liberates $\mathrm{C}{\mathrm{O}}_2$ from $\mathrm{NaHC}{\mathrm{O}}_3$ only if it is a stronger acid than carbonic acid ($\mathrm{p}{K}_{\mathrm{a}}$ ≈ 6.4). Benzenesulfonic acid ($\mathrm{p}{K}_{\mathrm{a}}$ ≈ -2), 2,4-dinitrophenol ($\mathrm{p}{K}_{\mathrm{a}}$ ≈ 4.1) and 4-methylbenzoic acid ($\mathrm{p}{K}_{\mathrm{a}}$ 4.4) are all stronger, so they evolve $\mathrm{C}{\mathrm{O}}_2$. Cyclohexanol ($\mathrm{p}{K}_{\mathrm{a}}$ ≈ 17) is far weaker than carbonic acid, so it does not react.