Q34 / 150 · MHT CET 2024 (03 May Shift 1) · Chemistry

Which from the following statements is correct for aqueous solution of $6 \mathrm{gL}^{-1}$ urea and $17 \cdot 12 \mathrm{~g} \mathrm{~L}^{-1}$ of sucrose? [Molar mass of urea $=60 \mathrm{~g} \mathrm{~mol}^{-1}$ Molar mass of sucrose $=342 \mathrm{~g} \mathrm{~mol}^{-1}$ ]

  • A
    Osmotic pressure exhibited by urea solution is lower than that of sucrose solution.
  • Correct answer
    B
    Urea solution is hypertonic to sucrose solution,
  • C
    These solutions are isotonic.
  • D
    On doubling the concentration of sucrose solution it becomes hypertonic to urea solution.

Solution

$\mathrm{M}_{\text {urea }}=\frac{\text { mass of urea in solution }}{\text { molar mass of urea } \times \text { volume of solution (in } L \text { ) }}$ $=\frac{\frac{6 \mathrm{~g}}{60 \mathrm{~g} \mathrm{~mol}^{-1}}}{1 \text { Litre }}=0.1 \mathrm{~mol} \mathrm{~L}^{-1}$ $\mathrm{M}_{\text {sucrose }}=\frac{\text { mass of sucrose in solution }}{\text { molar mass of sucrose } \times \text { volume of solution (in } L \text { ) }}$ $=\frac{\frac{17.12 \mathrm{~g}}{342 \mathrm{~g} \mathrm{~mol}^{-1}}}{1 \mathrm{Litre}^2}=0.05 \mathrm{~mol} \mathrm{~L}^{-1}$ Urea has higher solute concentration $(0.1 \mathrm{M})$ than sucrose ( 0.05 M ). Thus, urea solution is hypertonic to sucrose.

Hence, the correct answer is option: 'B'.

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