5 g of urea is dissolved in one kg of water. Up to what temperature the solution may be cooled befor — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Moles of urea = $5 \text{ g} / 60 \text{ g/mol} = 0.0833 \text{ mol}$. Molality $m = 0.0833 \text{ mol} / 1 \text{ kg} = 0.0833 \text{ m}$. $\Delta T_f = K_f \times m = 1.86 \times 0.0833 = 0.155^\circ\text{C}$. The freezing point is $0 - 0.155 = -0.155^\circ\text{C}$. Therefore, correct answer is D.