Which of the following solutions shows positive deviation from Raoult's law ?

Options

A. Acetone + Aniline
B. Acetone + Ethanol
C. Water+ Nitric acid
D. Chloroform + Benzene

Explanation

To determine which of the following solutions shows positive deviation from Raoult's law, we need to understand the concept of Raoult's law and what constitutes positive deviation.

### Step 1: Understand Raoult's Law
Raoult's law states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent in the solution. Mathematically, it can be expressed as:
\[ P_{solution} = X_{solvent} \cdot P_{solvent}^0 \]
where \( P_{solution} \) is the vapor pressure of the solution, \( X_{solvent} \) is the mole fraction of the solvent, and \( P_{solvent}^0 \) is the vapor pressure of the pure solvent.

### Step 2: Define Positive Deviation
A solution exhibits positive deviation from Raoult's law when the vapor pressure of the solution is greater than what is predicted by Raoult's law. This occurs when the intermolecular forces between the different components of the solution (A-B interactions) are weaker than the intermolecular forces in the pure components (A-A and B-B interactions).

### Step 3: Analyze Intermolecular Forces
When two liquids are mixed, if the interaction forces between the molecules of the different liquids (A-B) are weaker than the interaction forces between the molecules of the same liquid (A-A or B-B), the solution will show positive deviation. This is because the weaker A-B interactions lead to an increase in the vapor pressure of the solution.

### Step 4: Identify the Example
From the given options, we need to identify a pair of liquids that will show positive deviation. The example provided in the video is a mixture of acetone and ethanol. In this case:
- The A-A interactions (acetone-acetone) and B-B interactions (ethanol-ethanol) are stronger than the A-B interactions (acetone-ethanol).
- Therefore, when acetone and ethanol are mixed, the vapor pressure of the resulting solution is higher than what would be predicted by Raoult's law.

### Conclusion
Based on the analysis, the solution that shows positive deviation from Raoult's law is the mixture of acetone and ethanol.

### Final Answer
The correct option is acetone and ethanol.

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