Which of the following can be measured by the Ostwald-Walker dynamic method

Options

A. Vapour pressure of the solvent
B. Relative lowering of vapour pressure
C. Lowering of vapour pressure
D. All of these

Explanation

To solve the question regarding the Ostwald-Walker dynamic method, we will follow these steps:

### Step 1: Understand the Ostwald-Walker Dynamic Method
The Ostwald-Walker dynamic method is a technique used in physical chemistry to measure certain properties of solutions, specifically related to vapor pressure.

### Step 2: Identify What is Measured
This method primarily measures the **relative lowering of vapor pressure** when a solute is added to a solvent. It does not measure the absolute vapor pressure of the solvent or the solute but rather how the vapor pressure of the solvent changes when a solute is introduced.

### Step 3: Define Relative Lowering of Vapor Pressure
Relative lowering of vapor pressure is defined as the difference in vapor pressure of the pure solvent and the vapor pressure of the solution, divided by the vapor pressure of the pure solvent. This can be mathematically expressed as:
\[ \text{Relative lowering of vapor pressure} = \frac{P_0 - P}{P_0} \]
where \( P_0 \) is the vapor pressure of the pure solvent and \( P \) is the vapor pressure of the solution.

### Step 4: Conclusion
Based on the understanding that the Ostwald-Walker dynamic method is specifically used to measure the relative lowering of vapor pressure, we can conclude that this is the property that can be measured by this method.

### Final Answer
The Ostwald-Walker dynamic method can measure the **relative lowering of vapor pressure**.

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