The system that forms maximum boiling azeotrope:

Options

A. 2% KCl solution in water
B. 90% ethanol + 10% water
C. 68% `HNO_(3)` + 32% water
D. 33% `HNO_(3)` + 67% water

Explanation

To determine the system that forms a maximum boiling azeotrope, we need to follow these steps:

### Step 1: Understand the concept of an azeotrope
An azeotrope is a mixture of two or more liquids that has a constant boiling point and composition throughout the distillation process. This means that when the mixture is boiled, the vapor produced has the same composition as the liquid mixture, making it impossible to separate the components by simple distillation.

**Hint:** Remember that an azeotrope can be either a minimum boiling or maximum boiling type based on the interaction between the components.

### Step 2: Identify the types of azeotropes
Azeotropes can be classified into two categories:
- Minimum boiling azeotropes: These occur when the mixture has a lower boiling point than either of the pure components.
- Maximum boiling azeotropes: These occur when the mixture has a higher boiling point than either of the pure components.

**Hint:** Focus on the boiling point behavior of the mixture compared to its individual components to determine the type of azeotrope.

### Step 3: Understand negative deviation from Raoult's Law
A maximum boiling azeotrope is associated with a negative deviation from Raoult's Law. This means that the vapor pressure of the mixture is lower than expected, leading to a higher boiling point.

**Hint:** Recall that negative deviation indicates stronger interactions between the components than between the molecules of the pure components.

### Step 4: Identify common maximum boiling azeotropes
One well-known example of a maximum boiling azeotrope is the mixture of hydrochloric acid (HCl) and water. This mixture forms a maximum boiling azeotrope at a specific composition (approximately 32% HCl and 68% water).

**Hint:** Memorize common maximum boiling azeotropes, as they often appear in exam questions.

### Step 5: Conclusion
Based on the understanding of azeotropes and the specific example of hydrochloric acid and water, we conclude that the system that forms a maximum boiling azeotrope is the mixture of hydrochloric acid and water.

**Final Answer:** The system that forms a maximum boiling azeotrope is hydrochloric acid and water.