An ideal solution of two liquids is a solution in which each component obeys Raoult's which states that the vapour pressure of any component in the solution depends on the mole fraction of that component in the solution and the vapour pressure of that component in the pure state. However, there are many solution which do not obey Raoult's law. In other words, they show deviations from ideal behaviour which may be positive or negative. However, in either case, corresponding to a particular composition, they form a constant boiling mixtures called azeotropes.
Which of the following mixture do you expect will not show positive deviation from Raoult's law ?

Options

A. Benzene - Chloroform
B. Benzene - Acetone
C. Benzene - Ethanol
D. Benzene - Carbon tetrachloride

Explanation

To determine which mixture will not show positive deviation from Raoult's law, we need to understand the concepts of positive and negative deviations in solutions.

### Step-by-Step Solution:

1. **Understand Raoult's Law**: Raoult's law states that the vapor pressure of a component in a solution is directly proportional to its mole fraction in the solution and its vapor pressure in the pure state.

2. **Define Positive and Negative Deviations**:
- **Positive Deviation**: Occurs when the vapor pressure of the solution is higher than expected. This happens when the interactions between solute-solute or solvent-solvent are stronger than the solute-solvent interactions.
- **Negative Deviation**: Occurs when the vapor pressure of the solution is lower than expected. This happens when the solute-solvent interactions are stronger than the solute-solute or solvent-solvent interactions.

3. **Evaluate the Given Mixtures**:
- **Option 1: Benzene and Chloroform**: This mixture shows negative deviation from Raoult's law.
- **Option 2: Benzene and Acetone**: This mixture shows positive deviation from Raoult's law.
- **Option 3: Benzene and Ethanol**: This mixture also shows positive deviation from Raoult's law.
- **Option 4: Benzene and Carbon Tetrachloride**: This mixture shows positive deviation from Raoult's law.

4. **Identify the Correct Answer**: Since we are looking for a mixture that does not show positive deviation, we find that **Option 1 (Benzene and Chloroform)** is the only mixture that shows negative deviation.

### Final Answer:
The mixture that will not show positive deviation from Raoult's law is **Benzene and Chloroform**.

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