Among the following compounds, which has the maximum number of sp-hybridized C atoms ?

Options

A. `(CN)_2`
B. `CH_2=C=CH-CN`
C. `HC-=C-CH_2CH=CH_2`
D. `HC-=C-CN`

Answer

To determine which of the given compounds has the maximum number of sp-hybridized carbon atoms, we will analyze each option step by step.

### Step 1: Analyze Option A (Cn whole twice)
1. **Structure**: The compound is C2N2 (assuming Cn means C2N2).
2. **Identify Carbon Atoms**: There are 2 carbon atoms.
3. **Calculate Steric Number**:
- Each carbon forms 2 sigma bonds (one with another carbon and one with nitrogen).
- Steric number = Number of sigma bonds + Number of lone pairs = 2 + 0 = 2.
4. **Determine Hybridization**:
- Since the steric number is 2, the hybridization is sp.
5. **Conclusion**: There are **2 sp-hybridized carbon atoms**.

### Step 2: Analyze Option B
1. **Structure**: Let's assume the compound is C3H4 (like propene).
2. **Identify Carbon Atoms**: There are 3 carbon atoms.
3. **Calculate Steric Number**:
- The leftmost carbon forms 3 sigma bonds (steric number = 3, sp2).
- The middle carbon forms 2 sigma bonds (steric number = 2, sp).
- The rightmost carbon forms 3 sigma bonds (steric number = 3, sp2).
4. **Conclusion**: There are **2 sp-hybridized carbon atoms**.

### Step 3: Analyze Option C
1. **Structure**: Let's assume the compound is C4H6 (like butyne).
2. **Identify Carbon Atoms**: There are 4 carbon atoms.
3. **Calculate Steric Number**:
- The leftmost carbon forms 2 sigma bonds (steric number = 2, sp).
- The next two carbons each have a steric number of 3 (sp2).
- The rightmost carbon forms 2 sigma bonds (steric number = 2, sp).
4. **Conclusion**: There are **2 sp-hybridized carbon atoms**.

### Step 4: Analyze Option D
1. **Structure**: Let's assume the compound is C3H6 (like propyne).
2. **Identify Carbon Atoms**: There are 3 carbon atoms.
3. **Calculate Steric Number**:
- Each of the three carbon atoms forms 2 sigma bonds (steric number = 2, sp).
4. **Conclusion**: There are **3 sp-hybridized carbon atoms**.

### Final Conclusion
After analyzing all options, we find:
- Option A: 2 sp-hybridized carbon atoms.
- Option B: 2 sp-hybridized carbon atoms.
- Option C: 2 sp-hybridized carbon atoms.
- Option D: 3 sp-hybridized carbon atoms.

Thus, the compound with the maximum number of sp-hybridized carbon atoms is **Option D**.

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