1,2-butadiene has

Options

A. `sp^2` and `sp^3` hybridised carbon atom
B. `sp,sp^2` and `sp^3` hybridised carbon atoms
C. Only sp hybridised carbon atoms
D. Only `sp^2` hybridised carbon atoms

Answer

To solve the question regarding the hybridization and structure of 1,2-butadiene, we can break it down step by step.

### Step-by-Step Solution:

1. **Identify the Structure of 1,2-butadiene**:
- 1,2-butadiene is an organic compound with the formula C4H6. It consists of four carbon atoms and has two double bonds.
- The structure can be represented as:
\[ \text{CH}_2= \text{CH}-\text{CH}=\text{CH}_2 \]

2. **Determine the Hybridization of Carbon Atoms**:
- In 1,2-butadiene, we have four carbon atoms.
- The first and last carbon atoms (C1 and C4) are involved in double bonds and are connected to two hydrogen atoms each. These carbon atoms are **sp² hybridized** because they form three sigma bonds (two with hydrogen and one with another carbon) and have one unhybridized p orbital for the pi bond.
- The middle carbon atoms (C2 and C3) are also **sp² hybridized** for the same reasons.

3. **Count the Sigma and Pi Bonds**:
- Each carbon-carbon single bond contributes one sigma bond.
- Each carbon-carbon double bond consists of one sigma bond and one pi bond.
- Therefore, in 1,2-butadiene:
- There are 3 sigma bonds from C1 to C2, C2 to C3, and C3 to C4.
- There are 2 pi bonds (one from C1=C2 and one from C3=C4).

4. **Conclusion on Hybridization**:
- All four carbon atoms in 1,2-butadiene are **sp² hybridized**.
- The presence of double bonds indicates that these carbons have a trigonal planar geometry around them.

### Final Answer:
The hybridization of the carbon atoms in 1,2-butadiene is **sp²** for all four carbon atoms.

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