The osmotic pressure of a non-aqueous solution is measured by

Options

A. Berkeley and Hartley method
B. Pfeffer's method
C. Morse and Frazer method
D. Townend's method

Explanation

To determine the osmotic pressure of a non-aqueous solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Osmotic Pressure**:
- Osmotic pressure is defined as the minimum pressure required to stop the flow of solvent from a dilute solution to a more concentrated solution through a semi-permeable membrane.

2. **Identifying Measurement Methods**:
- There are several methods to measure osmotic pressure, including Berkeley and Hadley method, Tifers method, Morse and Fraser method, and Townhend's method.

3. **Analyzing Each Method**:
- **Berkeley and Hadley Method**: This method is primarily used for measuring the osmotic pressure of aqueous solutions, utilizing copper hexasulphate as a semi-permeable membrane.
- **Tifers Method**: Similar to the Berkeley and Hadley method, this method is also used for aqueous solutions.
- **Morse and Fraser Method**: This method, like the previous two, is designed for aqueous solutions and employs a similar approach.
- **Townhend's Method**: This method is specifically used for measuring osmotic pressure in non-aqueous solutions. It utilizes powdered glass as a semi-permeable membrane.

4. **Conclusion**:
- Based on the analysis, the method used to measure the osmotic pressure of a non-aqueous solution is **Townhend's method**.

### Final Answer:
The osmotic pressure of a non-aqueous solution is measured by **Townhend's method**.

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