Electron gain enthalpy of noble gases in positive . Explain.

Explanation

### Step-by-Step Solution:

1. **Definition of Electron Gain Enthalpy**:
- Electron gain enthalpy refers to the amount of energy released when an electron is added to the valence shell of an isolated gaseous atom. If energy is released, the value is negative; if energy is absorbed, the value is positive.

2. **Understanding Noble Gases**:
- Noble gases (such as Helium, Neon, Argon, etc.) have a complete valence shell configuration. For example, Neon has the electron configuration of 1s² 2s² 2p⁶, which means its outermost shell is fully filled.

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