The normal freezing point of nitrobenzene is 278.82 K. A non-volatile solute is dissolved in it and — Solutions and Colligative Properties Chemistry Question
Question
The normal freezing point of nitrobenzene is 278.82 K. A non-volatile solute is dissolved in it and a solution of molality 0.25 m is prepared. If the observed freezing point of the solution is 276.82 K, $K_f$ of nitrobenzene is
Answer: B
💡 Solution & Explanation
The freezing point depression $\Delta T_f = 278.82 - 276.82 = 2.00 \text{ K}$. Given molality $m = 0.25 \text{ m}$. Using the formula $\Delta T_f = K_f \times m$, we have $K_f = \Delta T_f / m = 2.00 / 0.25 = 8.0 \text{ K-kg mol}^{-1}$. Therefore, correct answer is B.
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