\(XY\) is the membrane / partition between two chambers 1 and 2 containing sugar solutions of concentration \(\mathrm{c}_{1}\) and \(\mathrm{c}_{2}\left(\mathrm{c}_{1}>\mathrm{c}_{2}\right) \mathrm{mol} \mathrm{L}^{-1}\). For the reverse osmosis to take place identify the correct condition (Here \(\mathrm{p}_{1}\) and \(\mathrm{p}_{2}\) are pressures applied on chamber 1 and 2) (A) Membrane/Partition ; Cellophane, \(\mathrm{p}_{1}>\pi\) (B) Membrane/Partition; Porous. \(\mathrm{p}_{2}>\pi\) (C) Membrane/Partition; Parchment paper, \(\mathrm{p}_{1}>\pi\) (D) Membrane/Partition : Cellophane, \(\mathrm{p}_{2}>\pi\) Choose the correct answer from the option given below:

JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Solutions

X Y

is the membrane / partition between two chambers 1 and 2 containing sugar solutions of concentration

c_{1}

and

c_{2} (c_{1} > c_{2}) mol 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,

p_{1} > π

(B) Membrane/Partition; Porous.

p_{2} > π

p_{1} > π

(D) Membrane/Partition : Cellophane,

p_{2} > π

Choose the correct answer from the option given below:

(A)B and D only
(B)A and D only
(C)A and C only✓ Correct
(D)C only

Answer: (C)

Solution

A semipermeable membrane such as cellophane or parchment paper allows only solvent molecules to pass, whereas a porous partition lets solute through as well and cannot sustain osmosis. In normal osmosis the solvent moves from the dilute side (chamber 2) into the concentrated side (chamber 1); to drive the flow backwards an external pressure larger than the osmotic pressure must be applied on the concentrated side, that is

p_{1} > π

acting on chamber 1. The two conditions that meet both requirements are a cellophane membrane with

p_{1} > π

and a parchment-paper membrane with

p_{1} > π

JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Single correct option

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JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Solutions

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