Why does pressure have no significant effect on the solubility of a solid in a liquid?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Solids and liquids are highly incompressible.
Pressure changes a system only when its volume can change. Solids and liquids are highly incompressible, so a change in pressure leaves them practically unaffected and the amount of solid that dissolves stays the same. Gases are different: they are compressible, and their solubility rises with pressure (Henry’s law).
Why the other options are incorrect
Option (1) The dissolution of a solid in a liquid is an endothermic process. — Incorrect. Dissolution may be endothermic or exothermic; this decides how solubility changes with temperature, not with pressure.
Option (2) Solid solutes are non-volatile, so they do not pass into the vapour phase. — Incorrect. Non-volatility of the solute explains the lowering of vapour pressure of the solvent, not the effect of pressure on solubility.
Option (4) Solid solutes have much larger molar masses than gaseous solutes. — Incorrect. Molar mass has nothing to do with it; what matters is that solids and liquids hardly change in volume under pressure, while gases do.
NCERT (2026-27 edition):
1.3.1 Solubility of a Solid in a Liquid – “Pressure does not have any significant effect on solubility of solids in liquids. It is so because solids and liquids are highly incompressible and practically remain unaffected by changes in pressure.”