Question

In a mixture of A and B, components show negative deviation when ______.

Options

• A-B interaction is stronger than A-A and B-B interaction.

• A-B interaction is weaker than A-A and B-B interaction.

• `Delta V_"mix" > 0`, `Delta S_"mix" > 0`

• `Delta V_"mix" = 0`, `Delta S_"mix" > 0`

Answer 1

A-B interaction is stronger than A-A and B-B interaction.

Explanation:

A negative deviation from Raoult’s law occurs when the intermolecular forces between A and B are stronger than those between A-A or B-B. This leads to a lower vapour pressure than expected because molecules are held together more tightly, escaping less into the vapour phase.