The liquid pair benzene-toluene shows

Options

A. Irregular deviation from Raoult’s law
B. Negative deviation from Raoult’s law
C. Positive deviation from Raoult’s law
D. Practically no deviation from Raoult’s law

Answer

To solve the question regarding the liquid pair benzene-toluene and its behavior according to Raoult's law, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Raoult's Law**:
Raoult's law states that the vapor pressure of an ideal solution is directly proportional to the mole fraction of the solvent. This means that in an ideal solution, the components behave independently and their interactions do not affect the overall vapor pressure significantly.

**Hint**: Remember that Raoult's law applies to ideal solutions where the interactions between different molecules are similar to those between like molecules.

2. **Identify Ideal vs Non-Ideal Solutions**:
- **Ideal Solutions**: These solutions obey Raoult's law throughout the entire concentration range. They typically consist of components with similar molecular structures and interactions.
- **Non-Ideal Solutions**: These solutions do not obey Raoult's law and can show either positive or negative deviations based on the interactions between the different components.

**Hint**: Think about the molecular structures of the components in the solution to determine if they are similar enough to behave ideally.

3. **Analyze the Structures of Benzene and Toluene**:
- Benzene has a molecular structure represented by a hexagonal ring (C6H6).
- Toluene has a similar structure but with a methyl group (CH3) attached to the benzene ring (C7H8).
- The similarity in their structures suggests that they will interact similarly, which is a key characteristic of ideal solutions.

**Hint**: Compare the molecular structures of benzene and toluene to see if they have similar functional groups and bonding.

4. **Determine the Type of Deviation**:
Since benzene and toluene have similar molecular structures, they are likely to form an ideal solution. Therefore, they do not show significant deviations from Raoult's law.

**Hint**: Recall that positive deviations occur when the interactions between different molecules are weaker than those between like molecules, while negative deviations occur when they are stronger.

5. **Select the Correct Option**:
Given the analysis, the correct conclusion is that benzene and toluene do not show any significant deviations from Raoult's law, which aligns with the fourth option stating "practically no deviation from Raoult's law."

**Hint**: Always refer back to the definitions of ideal and non-ideal solutions when selecting your answer.

### Final Answer:
The liquid pair benzene-toluene shows practically no deviation from Raoult's law, making option four the correct choice.