$X Y$ is the membrane / partition between two chambers 1 and 2 containing sugar solutions of concentration $c_1$ and $c_2\left(c_1 \gt c_2\right) \mathrm{mol} \mathrm{L}^{-1}$. For the reverse osmosis to take place identify the correct condition
(Here $p_1$ and $p_2$ are pressures applied on chamber 1 and 2)

(A) Membrane/Partition; Cellophane, $\mathrm{p}_1 \gt \pi$
(B) Membrane/Partition ; Porous. $\mathrm{p}_2 \gt \pi$
(C) Membrane/Partition ; Parchment paper, $\mathrm{p}_1 \gt \pi$
(D) Membrane/Partition : Cellophane, $\mathrm{p}_2 \gt \pi$
Choose the correct answer from the option given below :

• A

  B and D only
• B

  A and D only
• Correct answer
  C

  A and C only
• D

  C only

Solution

Normal osmosis occurs from (2) to (1)
For reverse osmosis from (1) to (2)
Pressure : $\mathrm{P}_1 \gt \pi$
$\therefore$ Answer [A \& C] only

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