An azeotropic solution of two liquid has boiling point lower than either of them when it

Options

A. shows negative deviation from Raoult's law
B. shows positive deviation from Raoult's low
C. shows ideal behaviour
D. is saturated

Explanation

To solve the question regarding the azeotropic solution of two liquids having a boiling point lower than either of them, we can break down the solution into the following steps:

### Step 1: Understand Azeotropes
An azeotropic mixture is a combination of two or more liquids that has a constant boiling point and composition in both the liquid and vapor phases. This means that when the mixture is boiled, the vapor produced has the same composition as the liquid mixture.

**Hint:** Azeotropes maintain the same composition in both liquid and vapor phases.

### Step 2: Identify the Behavior of Azeotropes
Azeotropes can exhibit either positive or negative deviation from Raoult's law. In this case, we are interested in when the boiling point of the azeotropic solution is lower than that of either of the pure components.

**Hint:** Azeotropes can show positive or negative deviations from ideal behavior.

### Step 3: Positive Deviation from Raoult's Law
When a mixture shows positive deviation from Raoult's law, it means that the observed vapor pressure of the mixture is greater than what would be expected based on the pure components. This results in a lower boiling point for the azeotropic solution compared to the boiling points of the individual liquids.

**Hint:** Positive deviation indicates that the interactions between different molecules in the mixture are weaker than the interactions between like molecules.

### Step 4: Conclusion
Therefore, an azeotropic solution of two liquids has a boiling point lower than either of them when it shows positive deviation from Raoult's law.

**Final Answer:** The azeotropic solution has a boiling point lower than either of the pure liquids when it shows positive deviation from Raoult's law.