JEE Main · 2026 · 08 Apr 2026 · Shift 2 · Solutions

For water $K_b=0.512\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$ while $K_f=1.86\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$, so $K_b$ is smaller than $K_f$ and the claim that $K_b$ exceeds $K_f$ is wrong. For the same solution the boiling-point elevation and freezing-point depression are $\Delta T_b=K_{b}m$ and $\Delta T_f=K_{f}m$, so the smaller $K_b$ makes $\Delta T_b$ smaller than $\Delta T_f$; the claim that the elevation is larger than the depression is therefore also wrong. Osmotic pressure, being measurable at very low concentrations and at ordinary temperatures, is indeed the colligative property of choice for the molar masses of proteins and polymers, so that statement is correct. Benzoic acid in benzene associates as a cyclic dimer in which the two carboxyl groups are joined by a pair of $\mathrm{O}-\mathrm{H}\cdots \mathrm{O}=\mathrm{C}$ hydrogen bonds; a drawing that does not show this cyclic, doubly hydrogen-bonded arrangement does not represent the dimer correctly. The incorrect statements are the one on $K_b$ versus $K_f$, the one on elevation versus depression, and the one depicting the benzoic acid dimer.