The mixture which shows positive deviation from Raoult's law is:

Options

A. Ethanol+Acetone
B. Benzene+Toluene
C. Acetone+Chloroform
D. Chloroethane+Bromoethane

Answer

To determine which mixture shows positive deviation from Raoult's law, we need to understand the concept of positive and negative deviations in the context of vapor pressure and intermolecular forces.

### Step-by-Step Solution:

1. **Understanding Raoult's Law**:
Raoult's law states that the vapor pressure of a solvent in a solution is directly proportional to the mole fraction of the solvent. In an ideal solution, the vapor pressure of the solution is equal to the vapor pressure of the pure solvent multiplied by its mole fraction.

2. **Defining Positive Deviation**:
A positive deviation from Raoult's law occurs when the vapor pressure of the solution is higher than expected. This indicates that the intermolecular forces between the solute and solvent are weaker than those in the pure components.

3. **Identifying Mixtures**:
We are given four mixtures, and we need to analyze them to see which one exhibits positive deviation. The mixtures typically consist of different combinations of solvents and solutes.

4. **Analyzing Ethanol and Acetone**:
- **Ethanol (C2H5OH)** has strong hydrogen bonding due to the -OH group.
- **Acetone (CH3COCH3)** has weaker dipole-dipole interactions.
- When mixed, the hydrogen bonding in ethanol is disrupted, leading to weaker interactions between ethanol and acetone compared to the interactions in pure ethanol.

5. **Conclusion**:
Since the attractive forces between ethanol and acetone are weaker than those in pure ethanol, the vapor pressure of the mixture increases. Therefore, the mixture of ethanol and acetone shows positive deviation from Raoult's law.

### Final Answer:
The mixture which shows positive deviation from Raoult's law is **Ethanol and Acetone**.