NEET2026ChemistryChapterActual
A liquid mixture of nitric acid ( HNO₃ ) and water is prepared. It is observed that the total vapour pressure of the solution is less than that predicted by Raoult's law. Which of the following is a correct characteristic of this solution?
Options
- AThe intermolecular attractive forces between HNO₃ and H₂O are weaker than those in the pure liquids.
- BThe process of mixing is accompanied by an absorption of heat ( H_ mix > 0 ).
- CThe escaping tendency of molecules from the surface of the solution is reduced compared to the pure liquids.
- DThe mixture will form a minimum boiling azeotrope at a specific composition.
Correct answer
C. The escaping tendency of molecules from the surface of the solution is reduced compared to the pure liquids.
Step-by-step solution
The solution of HNO₃ and water exhibits a total vapour pressure less than that predicted by Raoult's law, which indicates a negative deviation from Raoult's law. For solutions showing a negative deviation, the intermolecular attractive forces between the solute and solvent molecules (A-B interactions) are stronger than those in the pure liquids (A-A and B-B interactions). Due to these stronger intermolecular forces, the molecules are held more tightly in the liquid phase. Consequently, the escaping tendency of the