Which of the following process do not involve absorption of energy?

Options

A. `Cl(g) + e^(-) rarr Cl^(ɵ) (g)`
B. `S(g) +e^(-) rarr S^(ɵ)(g)`
C. `O(g) +e^(-) rarr O^(ɵ)(g)`
D. `O^(ɵ) + e^(-) rarr O^(2-)(g)`

Explanation

To determine which of the following processes do not involve the absorption of energy, we need to analyze the given reactions. The key concept here is understanding whether energy is released or absorbed during the process of an atom gaining an electron.

### Step-by-Step Solution:

1. **Identify the Processes**:
We are given four processes (reactions) involving the addition of electrons to neutral atoms. We need to analyze each reaction to see if energy is absorbed or released.

2. **Understanding Electron Affinity**:
- When a neutral atom gains an electron, it can either release energy (exothermic process) or absorb energy (endothermic process).
- Generally, the first electron added to a neutral atom (especially for electronegative elements) tends to release energy, while adding a second electron to an already negatively charged ion often requires energy due to electron-electron repulsion.

3. **Analyze Each Reaction**:
- **Reaction 1**: Chlorine gas + Electron → Chloride ion
- Chlorine is a highly electronegative atom. When it gains one electron, energy is released.
- **Reaction 2**: Sulfur + Electron → Sulfide ion
- Sulfur, like chlorine, is also electronegative. The addition of one electron releases energy.
- **Reaction 3**: Oxygen + Electron → Oxide ion
- Oxygen is also electronegative, and the addition of one electron releases energy.
- **Reaction 4**: Anion + Electron → Anion with an additional electron
- Here, the anion is gaining an additional electron. This process requires energy due to the repulsion between the negatively charged anion and the incoming electron.

4. **Conclusion**:
- The first three reactions (Chlorine, Sulfur, and Oxygen gaining one electron) involve the release of energy.
- The fourth reaction (the anion gaining an additional electron) involves the absorption of energy.
- Therefore, the processes that do not involve the absorption of energy are the first three: Chlorine, Sulfur, and Oxygen gaining one electron.

### Final Answer:
The processes that do not involve the absorption of energy are:
1. Chlorine gas + Electron
2. Sulfur + Electron
3. Oxygen + Electron