van der Waal's constant 'a' and 'b' are related with _____ respectively

Options

A. Attractive force and bond energy of molecules
B. Attractive force and volume of molecules
C. Volume and repulsive force of molecules
D. Shape and repulsive force of molecules

Answer

To solve the question regarding the van der Waals constants 'a' and 'b', we need to understand their significance in the van der Waals equation for real gases. The equation is given as:

\[ P + \frac{aN^2}{V^2} \times (V - Nb) = NRT \]

Where:
- \( P \) is the pressure of the gas,
- \( V \) is the volume,
- \( N \) is the number of moles,
- \( R \) is the ideal gas constant,
- \( T \) is the temperature,
- \( a \) is the van der Waals constant related to the attractive forces between molecules,
- \( b \) is the van der Waals constant related to the volume occupied by the gas molecules themselves.

### Step-by-Step Solution:

1. **Understanding the van der Waals Equation**:
The van der Waals equation modifies the ideal gas law to account for the interactions between gas molecules and the volume they occupy.

2. **Identifying the Role of 'a'**:
The constant 'a' in the equation accounts for the attractive forces between gas molecules. In an ideal gas, we assume no intermolecular forces, but in real gases, these forces can affect the pressure exerted by the gas.

3. **Identifying the Role of 'b'**:
The constant 'b' represents the volume occupied by the gas molecules themselves (excluded volume). It corrects for the fact that gas particles occupy space and cannot be compressed into zero volume.

4. **Conclusion**:
Therefore, van der Waals constant 'a' is related to the attractive forces between molecules, and 'b' is related to the excluded volume (the volume occupied by the gas molecules).

### Final Answer:
Van der Waals constants 'a' and 'b' are related to **attractive forces** and **excluded volume**, respectively.

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