How many `sigma` and `pi` bonds are there in the molecule `C_2 (CN)_4`?

Options

A. Five `sigma` and eight`pi`
B. Nine `sigma` and nine `pi`
C. Nine `sigma` and seven `pi`
D. Five `sigma` and nine `pi`

Answer

To determine the number of sigma (σ) and pi (π) bonds in the molecule C₂(CN)₄, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure**:
The molecule C₂(CN)₄ consists of two carbon atoms (C) and four cyano groups (CN). Each cyano group contains a carbon atom triple-bonded to a nitrogen atom.

2. **Analyze the Bonds**:
- **Carbon-Carbon Bonds**: There is one C-C bond between the two carbon atoms. This bond is a single bond, which means it is a sigma bond (1 σ bond).
- **Carbon-Nitrogen Bonds**: Each cyano group (CN) has a carbon atom triple-bonded to a nitrogen atom. A triple bond consists of one sigma bond and two pi bonds. Since there are four cyano groups, we will have:
- 4 CN groups × 1 σ bond = 4 σ bonds
- 4 CN groups × 2 π bonds = 8 π bonds

3. **Total the Bonds**:
- **Total Sigma Bonds**:
- From C-C bond: 1 σ
- From CN bonds: 4 σ
- Total σ bonds = 1 + 4 = 5 σ bonds
- **Total Pi Bonds**:
- From CN bonds: 8 π
- Total π bonds = 8 π bonds

4. **Final Count**:
- Total σ bonds = 5
- Total π bonds = 8

### Conclusion:
The molecule C₂(CN)₄ contains **5 sigma bonds** and **8 pi bonds**.