Acetylide ion `C_(2)^(2-)` has :

Options

A. `2sigma and 2 pi` bonds
B. `3 sigma and 1 pi` bonds
C. `1 sigma and 2 pi ` bonds
D. `2 sigma and 3 pi ` bonds

Answer

To determine the bonding in the acetylide ion \(C_2^{2-}\), we need to analyze the structure and the types of bonds formed between the carbon atoms.

### Step-by-Step Solution:

1. **Identify the Valence Electrons**:
Each carbon atom has 4 valence electrons. Since we have two carbon atoms in the acetylide ion and a total charge of -2, we need to account for the extra electrons due to the negative charge.
\[ \text{Total valence electrons} = 2 \times 4 + 2 = 10 \text{ electrons} \]

2. **Determine the Bonding**:
In the acetylide ion, the two carbon atoms will form a triple bond. A triple bond consists of one sigma bond and two pi bonds.

3. **Formation of the Bonds**:
- **Sigma Bond**: Formed by the head-on overlap of orbitals between the two carbon atoms.
- **Pi Bonds**: Formed by the sidewise overlap of the remaining p orbitals on each carbon atom.

4. **Count the Bonds**:
- From the triple bond between the two carbon atoms, we have:
- 1 sigma bond
- 2 pi bonds

5. **Conclusion**:
Therefore, the acetylide ion \(C_2^{2-}\) has 1 sigma bond and 2 pi bonds.

### Final Answer:
The acetylide ion \(C_2^{2-}\) has **1 sigma bond and 2 pi bonds**.

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