Which one of the following mixtures can be separated into pure components by fractional distillation?

Options

A. Benzene – toluene
B. Water – ethyl alcohol
C. Water – nitric acid
D. Water – hydrochloric acid

Answer

To determine which mixture can be separated into pure components by fractional distillation, we need to analyze the given options based on their boiling points and the nature of the components involved.

### Step-by-Step Solution:

1. **Understand Fractional Distillation**:
Fractional distillation is a technique used to separate mixtures of liquids that have different boiling points. It is particularly effective for separating components that have boiling points that are not too close to each other (typically a difference of at least 25°C).

2. **Analyze the Options**:
- **Option A: Benzene and Toluene**:
Both benzene and toluene are aromatic compounds. They have different boiling points (benzene: 80.1°C, toluene: 110.6°C). This significant difference in boiling points makes them suitable for separation by fractional distillation.

- **Option B: Water and Ethyl Alcohol**:
Water (100°C) and ethyl alcohol (78.37°C) have a boiling point difference of about 21.63°C. While they can be separated, the close boiling points may make fractional distillation less efficient.

- **Option C: Water and Nitric Acid**:
Water (100°C) and nitric acid (83°C) have a boiling point difference of approximately 17°C. This close boiling point difference makes it difficult to separate them effectively by fractional distillation.

- **Option D: Water and Hydrochloric Acid**:
Water (100°C) and hydrochloric acid (110°C) have a boiling point difference of about 10°C. This small difference also makes fractional distillation ineffective for separation.

3. **Conclusion**:
Based on the analysis, the mixture that can be effectively separated into pure components by fractional distillation is **Option A: Benzene and Toluene**.

### Final Answer:
**The correct option is A: Benzene and Toluene.**

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