The number of `sigma`-and `pi`-bond in 1-butene-3-yne is:

Options

A. `5 sigma` and `5 pi`
B. `7 sigma` and `3 pi`
C. `8 sigma` and `2 pi`
D. `6 sigma` and `4 pi`

Explanation

To determine the number of sigma (σ) and pi (π) bonds in 1-butene-3-yne, we can follow these steps:

### Step 1: Draw the Structure of 1-butene-3-yne
1-butene-3-yne has the following structure:
- The first part, "1-butene," indicates a four-carbon chain with a double bond between the first and second carbon atoms.
- The "3-yne" indicates a triple bond between the third and fourth carbon atoms.

The structure can be represented as:
```
H H H
| | |
H--C==C--C≡C--H
| |
H H
```

### Step 2: Identify Sigma Bonds
- **Single Bonds**: Each single bond (C-H or C-C) is a sigma bond.
- **Double Bonds**: Each double bond consists of one sigma bond and one pi bond.
- **Triple Bonds**: Each triple bond consists of one sigma bond and two pi bonds.

From the structure:
- There are 4 C-H single bonds (1 for each of the terminal CH groups).
- There are 3 C-C single bonds (1 between C1 and C2, 1 between C2 and C3, and 1 between C3 and C4).
- The double bond between C1 and C2 contributes 1 sigma bond.
- The triple bond between C3 and C4 contributes 1 sigma bond.

**Total Sigma Bonds Calculation**:
- C-H bonds: 4
- C-C single bonds: 3
- C=C double bond: 1
- C≡C triple bond: 1

Total σ bonds = 4 (C-H) + 3 (C-C) + 1 (C=C) + 1 (C≡C) = 9 σ bonds.

### Step 3: Identify Pi Bonds
- The double bond contributes 1 pi bond.
- The triple bond contributes 2 pi bonds.

**Total Pi Bonds Calculation**:
- C=C double bond: 1
- C≡C triple bond: 2

Total π bonds = 1 (from C=C) + 2 (from C≡C) = 3 π bonds.

### Conclusion
- The total number of sigma bonds in 1-butene-3-yne is 9.
- The total number of pi bonds in 1-butene-3-yne is 3.

### Final Answer
The number of sigma (σ) bonds is 9 and the number of pi (π) bonds is 3.

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