Glycerol is separated in soap industries by :

Options

A. Fractional distillation
B. Distillation under reduced pressure
C. Differential extraction
D. Steam distillation

Explanation

To solve the question of how glycerol is separated in soap industries, we will analyze the options provided and determine the most suitable method based on the properties of glycerol.

### Step-by-Step Solution:

1. **Understanding Glycerol**:
- Glycerol, also known as glycerin, has the chemical formula C3H8O3. It is a viscous liquid with a high boiling point of about 290°C.

2. **Analyzing the Options**:
- **Fractional Distillation**: This method is used to separate components of a mixture based on differences in boiling points. However, due to glycerol's high boiling point, this method may not be cost-effective.
- **Distillation Under Reduced Pressure**: This method allows for the distillation of substances at lower temperatures by reducing the pressure, which is beneficial for substances with high boiling points like glycerol. This method minimizes thermal degradation of the substance.
- **Differential Extraction**: This method involves separating components based on their solubility in different solvents. While it can be used for some separations, it is not the most common method for glycerol.
- **Steam Distillation**: This method is used for separating volatile compounds from non-volatile ones. Glycerol is not typically separated using this method due to its non-volatile nature.

3. **Choosing the Best Method**:
- Given that glycerol has a high boiling point and that thermal degradation can occur at high temperatures, the most suitable method for separating glycerol in the soap industry is **Distillation Under Reduced Pressure**. This method allows glycerol to be distilled at a lower temperature, making it more efficient and cost-effective.

### Final Answer:
Glycerol is separated in soap industries by **Distillation Under Reduced Pressure**.