Consider the following statements about semipermeable membranes and osmosis.
(A) Semipermeable membranes contain a network of submicroscopic holes or pores through which small solvent molecules, like water, can pass.
(B) Cellophane is an example of a synthetic semipermeable membrane.
(C) In osmosis, the solvent flows across the semipermeable membrane from the concentrated solution to the dilute solution.
(D) The pressure that just stops the flow of solvent into a solution across a semipermeable membrane is called the osmotic pressure of the solution.
Which of the statements given above are correct? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A), (B) and (D) only
A semipermeable membrane lets small solvent molecules through but hinders the bigger solute molecules. Solvent then moves across it from the dilute side to the concentrated side; this flow is osmosis.
(A) Semipermeable membranes contain a network of submicroscopic holes or pores through which small solvent molecules, like water, can pass. — True. The membranes look like continuous sheets, but their pores let solvent molecules through.
(B) Cellophane is an example of a synthetic semipermeable membrane. — True. Pig’s bladder and parchment are natural membranes; cellophane is synthetic.
(C) In osmosis, the solvent flows across the semipermeable membrane from the concentrated solution to the dilute solution. — False. The solvent flows from the dilute solution to the concentrated solution, that is, from lower to higher concentration.
(D) The pressure that just stops the flow of solvent into a solution across a semipermeable membrane is called the osmotic pressure of the solution. — True. This extra pressure on the solution side is the osmotic pressure.
NCERT (2026-27 edition):
1.6.4 Osmosis and Osmotic Pressure – “…These membranes can be of animal or vegetable origin and these occur naturally such as pig’s bladder or parchment or can be synthetic such as cellophane. These membranes appear to be continuous sheets or films, yet they contain a network of submicroscopic holes or pores. Small solvent molecules, like water, can pass through these holes but the passage of bigger molecules like solute is hindered.”
“The flow of the solvent from its side to solution side across a semipermeable membrane can be stopped if some extra pressure is applied on the solution. This pressure that just stops the flow of solvent is called osmotic pressure of the solution. The flow of solvent from dilute solution to the concentrated solution across a semipermeable membrane is due to osmosis.”