The following statements are based on the osmotic pressure of solutions. The correct statements are.........
(A) Molar concentration is same for isotonic solutions
(B) Solutions which have same osmotic pressure at same temperature are called isotonic solutions
(C) No osmosis occurs when isotonic solutions are separated by semi-permeable membrane
(D) A 1.9 % Sodium Chloride solution has equivalent osmotic pressure to that of fluid inside blood cells
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B) and (C) only
The osmotic pressure of a dilute solution is given by the van’t Hoff equation, where i is the van’t Hoff factor and C the molar concentration:
\( \displaystyle \pi = iCRT \)
Two solutions with the same osmotic pressure at the same temperature are called isotonic. Across a semipermeable membrane there is no net flow of solvent between them.
(A) Molar concentration is same for isotonic solutions — Incorrect. Isotonic solutions have the same \( iC \), the same concentration of solute particles, not necessarily the same molarity. For example, 0.1 M NaCl (i about 2) is nearly isotonic with 0.2 M glucose (i = 1).
(B) Solutions which have same osmotic pressure at same temperature are called isotonic solutions — Correct. This is the definition.
(C) No osmosis occurs when isotonic solutions are separated by semi-permeable membrane — Correct. With equal osmotic pressures on both sides, there is no net movement of solvent.
(D) A 1.9 % Sodium Chloride solution has equivalent osmotic pressure to that of fluid inside blood cells — Incorrect. The fluid inside blood cells is isotonic with 0.9% (mass/volume) NaCl, the normal saline. A 1.9% solution is hypertonic, and cells placed in it shrink as water flows out.
NCERT (2026-27 edition):
Osmosis and Osmotic Pressure – …
