Five per cent solution of a solute (X) is isotonic with 0.855% solution of sucrose (molecular weight — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Isotonic solutions have the same molarity. $C_1 = C_2 \implies \frac{w_1 / M_1}{V} = \frac{w_2 / M_2}{V} \implies \frac{5}{M_X} = \frac{0.855}{342} \implies M_X = \frac{5 \times 342}{0.855} = 2000$. Therefore, correct answer is D.