The system that forms maximum boiling azeotrope is: -

(a)- acetone - chloroform

(b)- ethanol - acetone

(c)- n-hexane – n-heptane

(d)- carbon disulfide – acetone.

An azeotrope is a special type of liquid mixture that boils at a constant temperature, just like a pure liquid. Let’s break it down:

• For solutions with a positive deviation from Raoult’s law, at some middle composition, the vapor pressure is highest and the boiling point is lowest.
• For solutions with a negative deviation, at some middle composition, the vapor pressure is lowest and the boiling point is highest.

In such mixtures, the liquid and vapor have the same composition at that special point. So when you boil it, the vapor condenses back into a liquid with the same composition. This kind of mixture is called a constant boiling mixture or azeotrope.

Types of Azeotropes:

• Minimum boiling azeotrope → Boiling point is lower than either pure component (from positive deviation).
• Maximum boiling azeotrope → Boiling point is higher than either pure component (from negative deviation).

Examples:

1. Acetone – chloroform → Negative deviation → Maximum boiling azeotrope
2. Ethanol – acetone → Positive deviation → Minimum boiling azeotrope
3. n-Hexane – n-Heptane → Ideal solution → No azeotrope
4. Carbon disulfide – acetone → Positive deviation → Minimum boiling azeotrope

Correct answer: Option A (Acetone – Chloroform)