van der Waals constant b in corrected equation for real gases represents

Options

A. measure of effective size of gas molecules
B. magnitude of attractive forces among gas molecules
C. free volume of the molecules
D. difference in pressure and volume of gas molecules.

Explanation

To solve the question regarding the van der Waals constant \( b \) in the corrected equation for real gases, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the van der Waals Equation**: The van der Waals equation for real gases is given by:
\[ \left(P + \frac{a}{V^2}\right)(V - b) = RT \]
Here, \( P \) is the pressure, \( V \) is the volume, \( T \) is the temperature, \( R \) is the universal gas constant, \( a \) is a constant that accounts for the attractive forces between gas molecules, and \( b \) is a constant that accounts for the volume occupied by the gas molecules themselves.

2. **Identify the Role of Constant \( b \)**: The constant \( b \) represents the volume occupied by one mole of gas molecules. It is often referred to as the "excluded volume" because it accounts for the fact that gas molecules have a finite size and cannot occupy the same space.

3. **Interpret the Meaning of \( b \)**: In essence, \( b \) signifies the effective size of gas molecules. It is a measure of the volume that is effectively "excluded" from being available for the movement of other gas molecules due to the presence of the gas molecules themselves.

4. **Conclusion**: Therefore, the van der Waals constant \( b \) represents the measure of the effective size of gas molecules.

### Final Answer:
The van der Waals constant \( b \) in the corrected equation for real gases represents the measure of the effective size of gas molecules.

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