The process requiring absorption of energy is:

Options

A. `N to N^(-)`
B. `F to F^(-)`
C. `Cl to Cl^(-)`
D. `H to H^(-)`

Explanation

To determine which process requires the absorption of energy, we need to analyze the stability of the reactants and products involved in the options provided. The absorption of energy typically indicates an endothermic process, where energy is required to make a reaction occur. Let's evaluate each option step by step.

### Step-by-Step Solution:

1. **Understanding the Concept of Endothermic Processes**:
- An endothermic process is one that requires energy input for the reaction to proceed. This usually occurs when the reactants are more stable than the products, necessitating energy absorption to facilitate the reaction.

2. **Analyzing Nitrogen (N)**:
- **Atomic Number**: 7
- **Electronic Configuration**: 1s² 2s² 2p³
- The 2p³ configuration is half-filled, which is a stable arrangement. To add an extra electron to nitrogen, energy must be absorbed because we are moving from a stable state to a less stable state (adding an electron to a half-filled orbital).

3. **Analyzing Fluorine (F)**:
- **Atomic Number**: 9
- **Electronic Configuration**: 1s² 2s² 2p⁵
- When fluorine gains an electron, it achieves a fully filled outer shell (2p⁶), which is very stable. The process of gaining an electron releases energy because the product (F-) is more stable than the reactant (F).

4. **Analyzing Chlorine (Cl)**:
- **Atomic Number**: 17
- **Electronic Configuration**: 1s² 2s² 2p⁶ 3s² 3p⁵
- Similar to fluorine, when chlorine gains an electron, it also achieves a stable electronic configuration (3p⁶). This process also releases energy.

5. **Analyzing Hydrogen (H)**:
- **Atomic Number**: 1
- **Electronic Configuration**: 1s¹
- When hydrogen gains an electron, it achieves a filled shell (1s²), which is stable. This process also releases energy.

6. **Conclusion**:
- Among the elements analyzed, nitrogen is the only one that requires energy absorption to add an electron due to its stable half-filled configuration. Therefore, the correct answer to the question is nitrogen.

### Final Answer:
The process requiring absorption of energy is the addition of an electron to nitrogen (N).

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