Match the column (Colligative Properties vs Aqueous solution; molality = molarity) — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Evaluate effective concentration ($i \times m$) for each. (P) $\text{Ca(NO}_3)_2$: $i=3 \implies 0.3 \text{ m}$. Thus $\Delta T_f = 0.3 K_f$ (A). (Q) NaBr: $i=2 \implies 0.28 \text{ m}$. Thus $\Delta T_b = 0.28 K_b$ (B). (R) $\text{MgCl}_2$: $i = 1 + 2(0.9) = 2.8 \implies 0.28 \text{ m}$. Thus $\Delta T_b = 0.28 K_b$ (B). (S) urea: $i=1 \implies 0.28 \text{ m}$. Thus $\Delta T_b = 0.28 K_b$ (B). (T) HA: $K_a = C\alpha^2 / (1-\alpha) \implies 0.81 = 0.1\alpha^2 / (1-\alpha) \implies \alpha = 0.9$, so $i=1.9 \implies 0.19 \text{ M}$. Thus $\pi = 0.19 RT$ (C). Equation (D) describes relative lowering of vapour pressure: $(P^\circ - P)/P^\circ = n/(n+N) = m/(m+1000/18)$. Since $m = \Delta T_f / K_f$, this equation is a universal identity for any aqueous solution, making it applicable to all five cases (P, Q, R, S, T). Therefore, correct answer is A-P, B-Q,R,S, C-T, D-P,Q,R,S,T.