Which of the following noble gases has the maximum positive electron gain enthalpy? (A) It is difficult to add an electron due to small size. (B) It is difficult to add an electron due to high electronegativity. (C) It is difficult to add an electron due to stable configuration. (d) It is difficult to add an electron due to high electron affinity

Options

A. It is difficult to add an electron due to small size.
B. It is difficult to add an electron due to high electronegativity.
C. It is difficult to add an electron due to stable configuration.
D. It is difficult to add an electron due to high electron affinity.

Explanation

To solve the question of which noble gas has the maximum positive electron gain enthalpy, we need to analyze the options provided based on the properties of noble gases.

### Step-by-Step Solution:

1. **Understanding Electron Gain Enthalpy**:
- Electron gain enthalpy refers to the energy change when an electron is added to a neutral atom. A positive electron gain enthalpy indicates that energy is required to add an electron, which is typically the case for noble gases due to their stable electronic configurations.

2. **Analyzing the Options**:
- **Option (A)**: "It is difficult to add an electron due to small size."
- This statement is incorrect. While smaller atoms may have higher ionization energies, the size of noble gases increases down the group, and size alone does not determine the electron gain enthalpy.

- **Option (B)**: "It is difficult to add an electron due to high electronegativity."
- This is also incorrect. Noble gases have very low electronegativity (close to zero) because they do not tend to attract electrons to form bonds. Thus, this option does not explain the positive electron gain enthalpy.

- **Option (C)**: "It is difficult to add an electron due to stable configuration."
- This statement is correct. Noble gases have a full valence shell (ns² np⁶ configuration), making them very stable. Adding an electron would disrupt this stable configuration, hence requiring energy (positive electron gain enthalpy).

- **Option (D)**: "It is difficult to add an electron due to high electron affinity."
- This is incorrect as well. Noble gases generally have very low or negligible electron affinity because they are already in a stable state and do not readily accept additional electrons.

3. **Conclusion**:
- The correct answer is **(C)**: "It is difficult to add an electron due to stable configuration." This explains why noble gases exhibit maximum positive electron gain enthalpy.