Which of the following is the correct statement?
A. The solubility of gases in liquids increases with a decrease of pressure.
B. If the dissolution process is endothermic, the solubility should increase with rise in temperature.
C. If the dissolution process is endothermic, the solubility should decrease with rise in temperature.
D. If the dissolution process is exothermic, the solubility will not change with a increase in temperature.
E. If the dissolution process is exothermic, the solubility should increase with an increase in temperature.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → B only
The solubility of a solid in a liquid at equilibrium follows Le Chatelier’s principle. If dissolution is endothermic (ΔsolH > 0), raising the temperature shifts the equilibrium towards dissolving, so the solubility rises. If it is exothermic (ΔsolH < 0), the solubility falls with rise in temperature. For gases, Henry’s law says that solubility rises with the partial pressure of the gas.
(A) The solubility of gases in liquids increases with a decrease of pressure. — Incorrect. By Henry’s law (p = KHx) the solubility of a gas increases with an increase of pressure.
(B) If the dissolution process is endothermic, the solubility should increase with rise in temperature. — Correct. Heat is absorbed in dissolving, so heating favours dissolution.
(C) If the dissolution process is endothermic, the solubility should decrease with rise in temperature. — Incorrect. For an endothermic dissolution, heating shifts the equilibrium towards dissolving (Le Chatelier’s principle), so the solubility increases, not decreases.
(D) If the dissolution process is exothermic, the solubility will not change with a increase in temperature. — Incorrect. The solubility decreases with rise in temperature.
(E) If the dissolution process is exothermic, the solubility should increase with an increase in temperature. — Incorrect. For an exothermic process the solubility decreases on heating.
NCERT (2026-27 edition):
Solubility of a Solid in a Liquid – …
Solubility of a Gas in a Liquid – “… Henry was the first to give a quantitative relation between pressure and solubility of a gas in a solvent which is known as Henry’s law. The law states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution.”