Which of the following in an energy consuming process ?

Options

A. `O_((g)) +e^(-) rarr O_((g))^(ɵ)`
B. `Na_((g))^(o+) + e^(-) rarr Na_((g))`
C. `O_((g))^(ɵ) + e^(-) rarr O_((g))^(2-)`
D. `O_((g))^(2-) rarr O^(ɵ)+e^(-)`

Explanation

To determine which of the following processes is energy-consuming, we need to analyze each option based on whether they require energy input (endothermic) or release energy (exothermic).

### Step-by-Step Solution:

1. **Understanding Energy-Consuming Processes**:
- Energy-consuming processes are those that require energy to proceed. These are typically endothermic reactions where the enthalpy change (ΔH) is positive.

2. **Analyzing Option A**:
- Option A states that oxygen gas (O2) is gaining an electron to form O⁻ (oxide ion).
- This process releases energy in the form of electron affinity, making it an exothermic process.
- **Conclusion**: Option A is incorrect.

3. **Analyzing Option B**:
- Option B involves a sodium ion (Na⁺) gaining an electron to form a sodium atom (Na).
- The reverse of this process requires energy equal to the ionization energy, meaning that the forward reaction (Na⁺ + e⁻ → Na) releases energy.
- **Conclusion**: Option B is also incorrect.

4. **Analyzing Option C**:
- Option C discusses the addition of an electron to the uninegative O⁻ ion to form O²⁻ (doubly negatively charged anion).
- Since O⁻ is unstable and cannot accept another electron without external energy, energy must be supplied for this process to occur. Therefore, ΔH is positive.
- **Conclusion**: Option C is correct as it is an energy-consuming process.

5. **Analyzing Option D**:
- Option D is the reverse of the reaction in Option C, where O²⁻ loses an electron to become O⁻.
- This process releases energy, making it exothermic.
- **Conclusion**: Option D is incorrect.

### Final Answer:
The correct answer is **Option C**, as it is the only process that requires energy input.