Question

Two liquids $HNO_3\, (A)$ and water $(B)$ form a maximum boiling azeotrope when mixed in the ratio of $68\%$ and $32\%$ respectively. It means

• A. $A - B$ interactions are stronger than $A - A$ and $B - B$ interactions
• B. $A - B$ interactions are weaker than $A - A$ and $B - B$ interactions
• C. vapour pressure of solution is more than the pure components
• D. vapour pressure of solution is less since only one component vaporises

Answer 1

Answer: (A)

Since the new interactions $(A - B)$ are stronger than $(A - A)$ and $(B - B)$ interactions, the solution shows negative deviation, i.e. less vapour pressure and hence higher boiling point.