In the carbonyl group, the carbon atom undergoes

Options

A. sp hybridisation
B. `sp^2` hybridisation
C. `sp^3` hybridisation
D. `sp^3 `d hybridisation.

Answer

To determine the hybridization of the carbon atom in the carbonyl group (C=O), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure**: The carbonyl group consists of a carbon atom double-bonded to an oxygen atom (C=O). The general structure can be represented as R-C(=O)-R', where R and R' are hydrocarbon groups or hydrogen atoms.

2. **Count the Sigma Bonds**:
- In the carbonyl group, the carbon atom forms:
- 1 sigma bond with the oxygen atom (C=O).
- 1 sigma bond with the R group (R-C).
- 1 sigma bond with the R' group (C-R').
- Therefore, the total number of sigma bonds is 3.

3. **Consider Lone Pairs and Charges**:
- In the carbonyl group, the carbon atom does not have any lone pairs or formal charges.
- Thus, we do not add any additional counts for lone pairs or charges.

4. **Calculate the Steric Number**:
- The steric number is calculated as the sum of sigma bonds, lone pairs, and negative charges.
- Here, we have 3 sigma bonds, 0 lone pairs, and 0 charges.
- Steric number = 3 + 0 + 0 = 3.

5. **Determine the Hybridization**:
- Based on the steric number:
- If the steric number is 2, the hybridization is sp (linear geometry).
- If the steric number is 3, the hybridization is sp² (trigonal planar geometry).
- If the steric number is 4, the hybridization is sp³ (tetrahedral geometry).
- Since the steric number is 3, the hybridization of the carbon atom in the carbonyl group is sp².

### Final Answer:
The hybridization of the carbon atom in the carbonyl group is **sp²**.