Which of the following azeotropic solutions has the boiling point less than boiling point of the constituents A and B ?

Options

A. `CHCI_(3)andCH_(3)COCH_(3)`
B. `CS_(2)andCH_(3)COCH_(3)`
C. `CH_(3)CH_(2)OHandCH_(3)COCH_(3)`
D. `CH_(3)CHOandCS_(2)`

Explanation

To determine which azeotropic solutions have a boiling point less than the boiling points of their constituents A and B, we need to understand the concept of azeotropes and how they behave in terms of boiling points and vapor pressures.

### Step-by-Step Solution:

1. **Understanding Azeotropes**:
- An azeotropic solution 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, it vaporizes in the same ratio as it is present in the liquid phase.

2. **Boiling Point Comparison**:
- For an azeotropic solution to have a boiling point lower than that of its pure components (constituents A and B), it must exhibit a specific behavior in terms of vapor pressure.

3. **Vapor Pressure Consideration**:
- The vapor pressure of the azeotropic mixture must be higher than that of the individual components at the same temperature. This is because a higher vapor pressure at a given temperature indicates that the mixture can boil at a lower temperature.

4. **Positive Deviation from Raoult's Law**:
- Azeotropes that boil at a lower temperature than their constituents typically show positive deviation from Raoult's Law. This occurs when the intermolecular forces between different molecules (A and B) are weaker than those in the pure components (A-A and B-B interactions).

5. **Examples of Azeotropic Solutions**:
- Common examples of azeotropic mixtures that exhibit this behavior include:
- Acetone and water
- Ethanol and water
- Chloroform and acetone
- These mixtures have boiling points that are lower than the boiling points of the individual components.

6. **Conclusion**:
- Therefore, the azeotropic solutions that have a boiling point less than the boiling points of constituents A and B are those that show positive deviation from Raoult's Law, such as the mixtures mentioned above.