Which of the following does not show positive deviation form Raoult's law ?

Options

A. Phenol-aniline
B. Ethanol-acetone
C. Acetone-carbon disulphide
D. Methanol -water

Answer

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

### Step 1: Understand Raoult's Law
Raoult's law states that the partial vapor pressure of each component in an ideal solution is directly proportional to its mole fraction in the solution. In an ideal solution, the intermolecular forces between the different components are similar to those in the pure components.

### Step 2: Identify Positive and Negative Deviations
- **Positive Deviation**: Occurs when the vapor pressure of the solution is higher than predicted by Raoult's law. This typically happens when the intermolecular forces between different components (AB) are weaker than those in the pure components (AA and BB).
- **Negative Deviation**: Occurs when the vapor pressure of the solution is lower than predicted by Raoult's law, which usually happens when the intermolecular forces between different components are stronger than those in the pure components.

### Step 3: Analyze the Given Solutions
Let's analyze the options provided in the question (though not explicitly listed here, we can infer common examples):
1. **Ethanol and Acetone**: This shows positive deviation due to the absence of hydrogen bonding between the two.
2. **Acetone and Carbon Disulfide**: This also shows positive deviation due to the difference in polarity and weaker intermolecular forces.
3. **Methanol and Water**: This shows positive deviation as well, due to hydrogen bonding being disrupted.
4. **Phenol and Aniline**: This shows negative deviation because both form strong hydrogen bonds with each other.

### Step 4: Conclusion
From the analysis, the pair that does not show positive deviation from Raoult's law is **Phenol and Aniline**. Therefore, if this option is present, it is the correct answer.

### Final Answer
**Phenol and Aniline do not show positive deviation from Raoult's law.**