The total number of sigma bonds formed by `sp^2-sp^2` overlapping in 1, 3-butadiene is

Options

A. 5
B. 2
C. 3
D. 4

Answer

To solve the problem of finding the total number of sigma bonds formed by `sp^2-sp^2` overlapping in 1,3-butadiene, we can follow these steps:

### Step-by-Step Solution:

1. **Draw the Structure of 1,3-Butadiene:**
- 1,3-butadiene has four carbon atoms arranged in a chain with two double bonds between the first and second carbon and the third and fourth carbon.
- The structure can be represented as:
```
H2C=CH-CH=CH2
```

2. **Identify the Hybridization of Carbon Atoms:**
- In 1,3-butadiene, the first and second carbon atoms (C1 and C2) are involved in a double bond, and the same goes for the third and fourth carbon atoms (C3 and C4).
- Each of these carbon atoms (C1, C2, C3, C4) is `sp^2` hybridized because they are bonded to three other atoms (either carbon or hydrogen).

3. **Count the Sigma Bonds Formed by `sp^2-sp^2` Overlapping:**
- Each `sp^2` hybridized carbon forms:
- 1 sigma bond with the adjacent carbon (C1 with C2, C2 with C3, C3 with C4).
- 1 sigma bond with a hydrogen atom (C1 with H, C2 with H, C3 with H, C4 with H).
- Therefore, we can summarize the sigma bonds:
- C1-C2: 1 sigma bond (sp^2-sp^2)
- C2-C3: 1 sigma bond (sp^2-sp^2)
- C3-C4: 1 sigma bond (sp^2-sp^2)
- C1-H: 1 sigma bond (sp^2-1s)
- C2-H: 1 sigma bond (sp^2-1s)
- C3-H: 1 sigma bond (sp^2-1s)
- C4-H: 1 sigma bond (sp^2-1s)

4. **Total Count of Sigma Bonds:**
- The total number of sigma bonds formed by `sp^2-sp^2` overlapping is 3 (C1-C2, C2-C3, C3-C4).
- The hydrogen atoms contribute additional sigma bonds, but they are not `sp^2-sp^2` overlaps.

5. **Final Answer:**
- The total number of sigma bonds formed by `sp^2-sp^2` overlapping in 1,3-butadiene is **3**.