How many sigma and pi bonds are there in the molecule of tetracyano ethylene ? .

Options

A. `4sigma, 14pi`
B. `5sigma, 13 pi`
C. `8 sigma, 10 pi`
D. `9 sigma, 9pi`

Explanation

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

### Step 1: Understand the Structure of Tetracyanoethylene
Tetracyanoethylene consists of two carbon atoms (C) connected by a double bond, and each carbon atom is also bonded to two cyano groups (CN). The cyano group consists of a carbon triple-bonded to a nitrogen atom.

### Step 2: Identify the Bonds
1. **C-C Bond**: The bond between the two carbon atoms is a double bond, which consists of:
- 1 sigma bond
- 1 pi bond

2. **C≡N Bonds**: Each cyano group (CN) has a triple bond between carbon and nitrogen, which consists of:
- 1 sigma bond
- 2 pi bonds

Since there are four cyano groups attached to the two carbon atoms, we can calculate the bonds contributed by these groups.

### Step 3: Count the Bonds
- **C-C Bond**:
- 1 sigma bond
- 1 pi bond

- **C≡N Bonds**:
- Each cyano group contributes:
- 1 sigma bond + 2 pi bonds
- Total for 4 cyano groups:
- 4 sigma bonds (1 for each CN)
- 8 pi bonds (2 for each CN)

### Step 4: Summarize the Total Number of Bonds
- **Total Sigma Bonds**:
- From C-C bond: 1 sigma
- From 4 C≡N bonds: 4 sigma
- Total σ bonds = 1 + 4 = 5 sigma bonds

- **Total Pi Bonds**:
- From C-C bond: 1 pi
- From 4 C≡N bonds: 8 pi
- Total π bonds = 1 + 8 = 9 pi bonds

### Step 5: Final Count
- Total number of sigma bonds = 5
- Total number of pi bonds = 9

### Conclusion
In the molecule of tetracyanoethylene, there are **5 sigma bonds and 9 pi bonds**.

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