Consider the following statements regarding osmotic pressure :
(A) Molar mass of a protein can be determined using osmotic pressure method.
(B) The osmotic pressure is proportional to the molarity.
(C) Reverse osmosis occurs when a pressure larger than osmotic pressure is applied to the concentrated solution side.
(D) Edema occurs due to retention of water in tissue cells as a result of osmosis.
Choose the correct statements with reference to osmotic pressure :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B), (C) and (D)
Osmosis is the flow of solvent through a semipermeable membrane from the pure solvent (or a dilute solution) into a more concentrated solution. The osmotic pressure is the extra pressure that must be applied on the solution to stop this flow. For a dilute solution it obeys the van’t Hoff equation:
\( \displaystyle \pi=CRT=\frac{n_2}{V}RT \)
(A) Molar mass of a protein can be determined using osmotic pressure method. — Correct. From \( \pi=\frac{w_2RT}{M_2V} \), the molar mass is \( M_2=\frac{w_2RT}{\pi V} \). The method is preferred for proteins and polymers, because their solutions give a measurable osmotic pressure even when very dilute and the measurement is made at room temperature.
(B) The osmotic pressure is proportional to the molarity. — Correct. At a given temperature, π = CRT, where C is the molarity.
(C) Reverse osmosis occurs when a pressure larger than osmotic pressure is applied to the concentrated solution side. — Correct. Such a pressure pushes the solvent out of the solution through the membrane, the reverse of osmosis; this is used in the desalination of sea water.
(D) Edema occurs due to retention of water in tissue cells as a result of osmosis. — Correct. People who take a lot of salt retain water in tissue cells and intercellular spaces by osmosis; the resulting swelling is called edema.
NCERT (2026-27 edition):
Osmosis and Osmotic Pressure – …
