Which of the following statements are not correct? A. For water,...

For water, the molal elevation constant $K_b = 0.52 \text{ K kg mol}^{-1}$ and the molal depression constant $K_f = 1.86 \text{ K kg mol}^{-1}$. Thus, $K_b < K_f$. Statement A is incorrect.

For a solution with a given molality $m$ of a non-volatile solute, the elevation in boiling point is $\Delta T_b = K_b m$ and the depression in freezing point is $\Delta T_f = K_f m$. Since $K_b < K_f$, it follows that $\Delta T_b < \Delta T_f$. Statement B is incorrect.

Osmotic pressure measurement is preferred for determining the molar mass of macromolecules such as proteins and polymers because the measurement is done at room temperature and the magnitude of osmotic pressure is significant even for very dilute solutions. Statement C is correct.

In benzene, benzoic acid undergoes dimerization through intermolecular hydrogen bonding, forming a cyclic dimer with two hydrogen bonds. The structure given in statement D represents a linear association with only one hydrogen bond. Statement D is incorrect.

Therefore, statements A, B, and D are incorrect.

Answer: A, B and D only