Question

The diagram given below is a vapour pressure-composition graph for a binary solution of $A$ and $B$.

In the solution, A-B interactions are:

• A. Similar to $A-A$ and $B-B$ interactions
• B. Stronger than $A-A$ and $B-B$ interactions
• C. Weaker than $A-A$ and $B-B$ interactions
• D. Unpredictable

Answer 1

Answer: (C)

Correct option: (D) Weaker than $A-A$ and $B-B$ interactions
The vapour pressure and composition graph show that, as the mole fraction of B increases, vapour pressure also increases. So total vapour pressure of the solution will be greater than the vapour pressure of liquids A and B, which means it shows a positive deviation from Raoult's law and the interaction between the A and B molecules are weaker than A-A and B-B molecules.