The number of `pi` bonds in the structure given below are : `(NC)_2 C = C(CN)_2`

Options

A. 1
B. 9
C. 5
D. unpredictable.

Explanation

To determine the number of π-bonds in the structure (NC)₂C=C(CN)₂, we need to analyze the bonds present in the given molecular structure.

### Step-by-Step Solution:

1. **Identify the Structure**: The given structure can be broken down as follows:
- There are two (NC) groups attached to a central carbon-carbon double bond (C=C).
- Each (NC) group contains a carbon (C) bonded to a nitrogen (N) with a triple bond.

2. **Count the Types of Bonds**:
- **Double Bond (C=C)**:
- A double bond consists of 1 σ-bond and 1 π-bond.
- Therefore, from the double bond, we have **1 π-bond**.

- **Triple Bonds (C≡N)**:
- Each triple bond consists of 1 σ-bond and 2 π-bonds.
- In the structure, there are two (NC) groups, each contributing a triple bond.
- Thus, from the two (C≡N) bonds, we have:
- 2 (from the first NC) × 2 π-bonds = 4 π-bonds
- 2 (from the second NC) × 2 π-bonds = 4 π-bonds
- Therefore, from the two (C≡N) bonds, we have a total of **4 π-bonds**.

3. **Total π-bonds Calculation**:
- Now, we can sum the π-bonds from the double bond and the triple bonds:
- π-bonds from C=C: **1 π-bond**
- π-bonds from 2 (C≡N): **4 π-bonds**
- Total π-bonds = 1 (from C=C) + 4 (from C≡N) = **5 π-bonds**.

4. **Conclusion**:
- The total number of π-bonds in the structure (NC)₂C=C(CN)₂ is **5**.

### Final Answer:
The number of π-bonds in the structure (NC)₂C=C(CN)₂ is **5**.

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