Which of the following diatomic molecular species has only `pi` bonds according to Molecular orbital Theory

Options

A. `Be_(2)`
B. `O_(2)`
C. `N_(2)`
D. `C_(2)`

Explanation

To determine which diatomic molecular species has only pi bonds according to Molecular Orbital Theory (MOT), we will analyze the molecular orbital configurations of the given species: O2, N2, and C2.

### Step-by-Step Solution:

1. **Understanding Molecular Orbital Theory (MOT)**:
- In MOT, atomic orbitals combine to form molecular orbitals, which can be bonding or antibonding.
- Bonding orbitals are lower in energy and help stabilize the molecule, while antibonding orbitals are higher in energy and destabilize the molecule.

2. **Analyzing O2**:
- The electronic configuration of O2 is derived from the atomic configuration of oxygen, which is 1s² 2s² 2p⁴.
- In the MOT diagram for O2, the arrangement of electrons in the molecular orbitals is:
- σ(1s)², σ*(1s)², σ(2s)², σ*(2s)², (π(2p_x)², π(2p_y)²), σ(2p_z)¹
- O2 has one sigma bond and one pi bond, thus it does not have only pi bonds.

3. **Analyzing N2**:
- The electronic configuration of N2 is based on nitrogen, which is 1s² 2s² 2p³.
- The MOT diagram for N2 shows:
- σ(1s)², σ*(1s)², σ(2s)², σ*(2s)², (π(2p_x)², π(2p_y)²), σ(2p_z)¹
- N2 has one sigma bond and two pi bonds (due to the triple bond), thus it does not have only pi bonds.

4. **Analyzing C2**:
- The electronic configuration of C2 is based on carbon, which is 1s² 2s² 2p².
- The MOT diagram for C2 shows:
- σ(1s)², σ*(1s)², σ(2s)², σ*(2s)², (π(2p_x)², π(2p_y)²)
- C2 has two pi bonds and no sigma bonds, which means it consists only of pi bonds.

5. **Conclusion**:
- From the analysis, it is clear that the diatomic molecular species that has only pi bonds is **C2**.

### Final Answer:
**C2** is the diatomic molecular species that has only pi bonds according to Molecular Orbital Theory.