In steam distillation of toluene , the pressure of toluene in vapour is

Options

A. equal to the pressure of barometer
B. less than the pressure of barometer
C. equal to vapour pressure of toluene in simple distillation
D. more than vapour pressure of toluene in simple distillation

Explanation

To solve the question regarding the pressure of toluene in vapor during steam distillation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Steam Distillation**:
- In steam distillation, a mixture of steam and the volatile component (in this case, toluene) is used to separate the component from a non-volatile impurity or from a mixture. The steam helps in lowering the boiling point of the volatile component.

2. **Vapor Pressure Concept**:
- The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor are in equilibrium. For toluene, this vapor pressure is a key factor in determining the pressure in the vapor phase during steam distillation.

3. **Barometric Pressure**:
- The barometric pressure is the atmospheric pressure measured by a barometer. During steam distillation, the total pressure in the system is influenced by both the vapor pressure of the toluene and the pressure of the steam.

4. **Pressure Relationships**:
- In steam distillation, the pressure of the vapor (which includes the vapor of toluene and steam) is typically less than the barometric pressure. This is because the vapor pressure of toluene alone does not equal the total pressure in the system; the presence of steam reduces the effective pressure exerted by the toluene.

5. **Conclusion**:
- Therefore, the pressure of toluene in vapor during steam distillation is less than the barometric pressure. Thus, the correct answer to the question is that the pressure of toluene in vapor is less than the barometric pressure.

### Final Answer:
The pressure of toluene in vapor during steam distillation is **less than the barometric pressure**.

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