The number of `sp^2` hybridized carbon atoms in
`HC -= C - CH_2 - overset(O)overset(||)C-CH_2- CH= CH_2` is

Options

A. 3
B. 5
C. 4
D. 6

Explanation

To determine the number of `sp^2` hybridized carbon atoms in the given compound `HC ≡ C - CH₂ - C(=O) - CH₂ - CH = CH₂`, we will analyze the hybridization of each carbon atom step by step.

### Step 1: Identify the structure and count the carbon atoms
The structure of the compound can be broken down as follows:
- C1: HC (attached to one hydrogen and triple bonded to C2)
- C2: C (triple bonded to C1 and single bonded to C3)
- C3: CH₂ (single bonded to C2 and C4)
- C4: C(=O) (double bonded to oxygen and single bonded to C3 and C5)
- C5: CH₂ (single bonded to C4 and C6)
- C6: C (double bonded to C7 and single bonded to C5)
- C7: CH₂ (single bonded to C6 and double bonded to C8)

Counting the carbon atoms, we find there are a total of 7 carbon atoms.

### Step 2: Determine the hybridization of each carbon atom
1. **C1 (HC)**:
- Bonds: 1 C-H bond, 1 C-C bond (triple bond with C2)
- Hybridization: `sp` (1 sigma bond + 2 pi bonds)

2. **C2**:
- Bonds: 1 C-C bond (triple bond with C1), 1 C-C bond (single with C3)
- Hybridization: `sp` (1 sigma bond + 2 pi bonds)

3. **C3 (CH₂)**:
- Bonds: 2 C-H bonds, 1 C-C bond (single with C2)
- Hybridization: `sp³` (4 sigma bonds)

4. **C4 (C=O)**:
- Bonds: 1 C-C bond (single with C3), 1 C=O bond (1 sigma + 1 pi)
- Hybridization: `sp²` (3 sigma bonds)

5. **C5 (CH₂)**:
- Bonds: 2 C-H bonds, 1 C-C bond (single with C4)
- Hybridization: `sp³` (4 sigma bonds)

6. **C6**:
- Bonds: 1 C-C bond (double with C7), 1 C-C bond (single with C5)
- Hybridization: `sp²` (3 sigma bonds)

7. **C7 (CH₂)**:
- Bonds: 2 C-H bonds, 1 C-C bond (double with C6)
- Hybridization: `sp²` (3 sigma bonds)

### Step 3: Count the `sp²` hybridized carbon atoms
From the analysis:
- C4 is `sp²`
- C6 is `sp²`
- C7 is `sp²`

Thus, the total number of `sp²` hybridized carbon atoms is **3**.

### Final Answer
The number of `sp²` hybridized carbon atoms in the given compound is **3**.

---