Which of the following will have the most negative electron gain enthalpy and which the least negative ? P, S, Cl, F
Explain your answer.

Explanation

To determine which of the elements (P, S, Cl, F) has the most negative and least negative electron gain enthalpy, we need to understand the concept of electron gain enthalpy and how it varies across the periodic table.

### Step-by-Step Solution:

1. **Understanding Electron Gain Enthalpy**:
- Electron gain enthalpy is the energy change that occurs when an electron is added to a neutral atom in the gas phase. A more negative value indicates that energy is released when the electron is added, making the process more favorable.

2. **Trends in the Periodic Table**:
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