During change of `O_(2)` to `O_(2)^(2-)` ion, the electrons add on which of the following orbitals ?

Options

A. `pi^(**)` orbital
B. `pi`orbital
C. `sigma^(**)` orbital
D. `sigma` orbital.

Explanation

To determine the orbitals to which electrons are added during the conversion of \( O_2 \) to \( O_2^{2-} \), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electron Configuration of \( O_2 \)**:
- The molecular orbital (MO) configuration for \( O_2 \) is derived from the atomic orbitals of oxygen. The atomic configuration of oxygen is \( 1s^2 \, 2s^2 \, 2p^4 \).
- In \( O_2 \), the total number of electrons is 16 (8 from each oxygen atom).

2. **Construct the Molecular Orbital Diagram**:
- The molecular orbitals for \( O_2 \) are filled in the following order:
- \( \sigma_{1s}^2 \)
- \( \sigma_{1s}^* \)
- \( \sigma_{2s}^2 \)
- \( \sigma_{2s}^* \)
- \( \sigma_{2p_z}^2 \)
- \( \pi_{2p_x}^2 \)
- \( \pi_{2p_y}^2 \)
- \( \pi_{2p_x}^* \)
- \( \pi_{2p_y}^* \)

3. **Count the Electrons in \( O_2 \)**:
- The total number of electrons in \( O_2 \) is 16, which fills the molecular orbitals as follows:
- \( \sigma_{1s}^2 \)
- \( \sigma_{1s}^* \)
- \( \sigma_{2s}^2 \)
- \( \sigma_{2s}^* \)
- \( \sigma_{2p_z}^2 \)
- \( \pi_{2p_x}^2 \)
- \( \pi_{2p_y}^2 \)

4. **Determine the Change to \( O_2^{2-} \)**:
- When converting \( O_2 \) to \( O_2^{2-} \), we add 2 more electrons, bringing the total to 18 electrons.

5. **Identify the Orbitals for the Added Electrons**:
- The additional 2 electrons will fill the next available molecular orbitals, which are the anti-bonding orbitals \( \pi_{2p_x}^* \) and \( \pi_{2p_y}^* \).
- Therefore, the extra electrons are added to the \( \pi_{2p_x}^* \) and \( \pi_{2p_y}^* \) orbitals.

6. **Conclusion**:
- The electrons are added to the \( \pi^* \) (anti-bonding) orbitals, specifically \( \pi_{2p_x}^* \) and \( \pi_{2p_y}^* \).

### Final Answer:
The electrons add to the \( \pi^* \) orbitals (specifically \( \pi_{2p_x}^* \) and \( \pi_{2p_y}^* \)) during the conversion of \( O_2 \) to \( O_2^{2-} \).