Energy is released in the process of

Options

A. `Na_((g)) rarr Na_((g))^(+) +e`
B. `O_((g))^(-) +e rarr O_((g))^(-2)`
C. `O_((g)) +e rarr O_((g))^(-)`
D. `N_((g))^(-2) +e rarr N_((g))^(-3)`

Answer

To determine in which process energy is released, we need to analyze the reactions provided in the options. We will look at the concept of ionization energy and electron gain enthalpy.

### Step-by-step Solution:

1. **Understanding Ionization Energy and Electron Gain Enthalpy**:
- Ionization energy is the energy required to remove an electron from an atom. When energy is supplied to remove an electron, the process is endothermic, and the enthalpy change (ΔH) is positive.
- Electron gain enthalpy is the energy released when an electron is added to an atom. When energy is released during this process, it is exothermic, and the enthalpy change (ΔH) is negative.

2. **Analyzing the First Reaction**:
- The first option involves sodium (Na) losing one electron to form Na⁺. Since energy is required to remove an electron, this reaction is endothermic. Therefore, ΔH is positive.

3. **Analyzing the Second Reaction**:
- The second option involves O⁻ accepting one electron to form O²⁻. Adding an electron to an atom generally releases energy. However, if we consider that O⁻ is already negatively charged, adding another electron may require energy, making ΔH positive.

4. **Analyzing the Third Reaction**:
- The third option also involves O⁻ accepting one electron to form O²⁻. Similar to the second reaction, this process releases energy, so ΔH is negative.

5. **Analyzing the Fourth Reaction**:
- The fourth option involves O accepting one electron to form O⁻. This process releases energy, so ΔH is negative.

6. **Conclusion**:
- Among the reactions analyzed, the third option, where O⁻ accepts an electron to form O²⁻, is the process where energy is released (ΔH is negative). Therefore, the answer is the third option.

### Final Answer:
Energy is released in the process of the third option, where O⁻ accepts an electron to form O²⁻.