Identify the incorrect statement among the following?

Options

A. Van der Waal's constant 'a' is a measure of intermolecular force of attraction between the molecules.
B. Intermolecular force of attraction increases with the increase in pressure
C. Van der Waal's constant 'a' becomes negligible at high pressure.
D. None of these

Answer

To identify the incorrect statement among the given options, we will analyze each statement one by one based on our understanding of the Van der Waals equation and the behavior of gases.

### Step-by-Step Solution:

1. **Understanding the Van der Waals Equation**:
The Van der Waals equation for real gases is given by:
\[ \left( P + \frac{a n^2}{V^2} \right) (V - n b) = nRT \]
Here, \( P \) is the pressure, \( V \) is the volume, \( n \) is the number of moles, \( R \) is the universal gas constant, and \( a \) and \( b \) are Van der Waals constants specific to each gas.

2. **Analyzing Option A**:
- The statement is: "Van der Waals constant A is the measure of intermolecular forces of attraction between the molecules."
- This statement is **true** because the constant \( a \) accounts for the attractive forces between gas molecules. Therefore, this option is not the incorrect statement.

3. **Analyzing Option B**:
- The statement is: "Intermolecular force of attraction increases with increase in pressure."
- This statement is **false**. As pressure increases, the volume available to the gas molecules decreases, and the effect of intermolecular forces becomes less significant compared to the pressure exerted by the gas. Therefore, this option is the incorrect statement.

4. **Analyzing Option C**:
- The statement is: "Van der Waals constant A becomes negligible at high pressure."
- This statement is **true**. At high pressures, the term \( \frac{a n^2}{V^2} \) becomes negligible compared to \( P \) in the equation, which means the effect of intermolecular forces (represented by \( a \)) is less significant. Thus, this option is also correct.

### Conclusion:
The incorrect statement among the options is **Option B**: "Intermolecular force of attraction increases with increase in pressure."