A saturated solution of a solid whose dissolution is endothermic (ΔsolH > 0) is separated from the undissolved solid and then heated. The solution:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Becomes unsaturated
A saturated solution holds the maximum amount of solute that can dissolve at that temperature; an unsaturated solution can dissolve more.
When dissolution is endothermic (ΔsolH > 0), the solubility increases as the temperature rises.
Once the solution is separated from the undissolved solid, the amount of dissolved solute stays fixed. On heating, the solubility rises above this amount, so the same solution can now dissolve more solute: it has become unsaturated.
Why the other options are incorrect
Option (1) Remains saturated — Incorrect. To stay saturated, more solid would have to dissolve as the solubility rises, but no undissolved solid is left in contact with the solution.
Option (3) Becomes supersaturated — Incorrect. A supersaturated solution holds more solute than its solubility; here the solubility rises while the dissolved amount stays the same, so the solution holds less.
Option (4) Deposits some of the dissolved solute — Incorrect. Solute separates out only when the solubility falls, as on heating a solution whose dissolution is exothermic.
NCERT (2026-27 edition):
1.3.1 Solubility of a Solid in a Liquid – “… Such a solution in which no more solute can be dissolved at the same temperature and pressure is called a saturated solution. An unsaturated solution is one in which more solute can be dissolved at the same temperature.”
Effect of temperature – “The solubility of a solid in a liquid is significantly affected by temperature changes. … In general, if in a nearly saturated solution, the dissolution process is endothermic (ΔsolH > 0), the solubility should increase with rise in temperature and if it is exothermic (ΔsolH < 0) the solubility should decrease.”