A fractional column is used in :

Options

A. sublimation
B. distillation
C. fractional distillation
D. simple distillation.

Answer

To solve the question "A fractional column is used in:", we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding the Options**: The question presents four options, and we need to identify which process utilizes a fractional column.

2. **Evaluating Sublimation**:
- **Definition**: Sublimation is the process where a solid turns directly into a gas without passing through the liquid state.
- **Use of Fractional Column**: In sublimation, there is no need for separation of different components based on boiling points or volatility, so a fractional column is not used.
- **Conclusion**: Sublimation is not the correct answer.

3. **Evaluating Distillation**:
- **Definition**: Distillation is a separation process that relies on differences in boiling points of components in a mixture.
- **Simple Distillation**: This method is used when separating components with significantly different boiling points (typically greater than 25°C difference). A fractional column is not required for simple distillation.
- **Conclusion**: The option related to simple distillation is also not correct.

4. **Evaluating Fractional Distillation**:
- **Definition**: Fractional distillation is a technique used to separate a mixture of liquids into its individual components based on their different boiling points.
- **Use of Fractional Column**: A fractional column is essential in this process as it provides a larger surface area for repeated vaporization and condensation, allowing for better separation of components with closer boiling points.
- **Conclusion**: Fractional distillation is the correct answer.

5. **Final Answer**: Based on the analysis, the fractional column is used in **fractional distillation**.