How many `sigma and pi` bonds are present in tetra cyanoethylene ?

Options

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

Explanation

To determine the number of sigma (σ) and pi (π) bonds in tetra cyanoethylene, we can follow these steps:

### Step 1: Understand the Structure of Tetra Cyanoethylene
Tetra cyanoethylene is derived from ethylene (C2H4) with four cyano (CN) groups attached. The structure can be represented as follows:

```
N≡C
|
C=C
|
N≡C
```

### Step 2: Identify the Bonds in the Structure
1. **C=C Bond**: This is a double bond between the two carbon atoms.
2. **C≡N Bonds**: Each cyano group (CN) has a triple bond between carbon and nitrogen.

### Step 3: Count the Sigma Bonds
- **C=C Bond**: Contributes 1 σ bond.
- **C≡N Bonds**: Each triple bond contributes 1 σ bond. Since there are 4 cyano groups, this contributes 4 σ bonds.

**Total σ bonds**:
- From C=C: 1
- From 4 C≡N: 4
- **Total σ bonds = 1 + 4 = 5 σ bonds.**

### Step 4: Count the Pi Bonds
- **C=C Bond**: Contributes 1 π bond.
- **C≡N Bonds**: Each triple bond contributes 2 π bonds. Since there are 4 cyano groups, this contributes 8 π bonds.

**Total π bonds**:
- From C=C: 1
- From 4 C≡N: 8
- **Total π bonds = 1 + 8 = 9 π bonds.**

### Step 5: Final Count
- **Total σ bonds = 5**
- **Total π bonds = 9**

### Conclusion
In tetra cyanoethylene, there are **5 sigma bonds** and **9 pi bonds**.

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