Electron gain enthalpy usually becomes less negative from top to bottom in a group. Is there any exception to this generalization ? Comment.

Explanation

### Step-by-Step Solution:

1. **Understanding Electron Gain Enthalpy**:
- Electron gain enthalpy is defined as the amount of energy released when an electron is added to a neutral gaseous atom. It is usually expressed in kilojoules per mole (kJ/mol). A more negative value indicates that more energy is released when an electron is added.

2. **General Trend in Groups**:
- As we move down a group in the periodic table, the size of the atoms increases due to the addition of electron shells. This generally leads to a decrease in the attraction between the nucleus and the added electron, resulting in less negative electron gain enthalpy.

...