Which of the following compounds has a linear structure?

Options

A. `"CCl"_4`
B. `SO_2`
C. `C_2H_2`
D. `C_2H_4`

Explanation

To determine which compound has a linear structure, we will analyze the hybridization and steric number of each compound provided in the options.

### Step-by-Step Solution:

1. **Understanding Steric Number and Hybridization**:
- The steric number is calculated as the sum of the number of sigma bonds and lone pairs around the central atom.
- The hybridization can be determined based on the steric number:
- Steric number 2: sp hybridization (linear structure)
- Steric number 3: sp² hybridization (trigonal planar structure)
- Steric number 4: sp³ hybridization (tetrahedral structure)

2. **Analyzing Each Compound**:

**Option A: CCl₄**
- Carbon has 4 sigma bonds with chlorine and no lone pairs.
- Steric number = 4 (4 sigma bonds + 0 lone pairs).
- Hybridization = sp³.
- Structure = Tetrahedral (not linear).

**Option B: SO₂**
- Sulfur has 2 sigma bonds with oxygen and 1 lone pair.
- Steric number = 3 (2 sigma bonds + 1 lone pair).
- Hybridization = sp².
- Structure = Bent (not linear).

**Option C: C₂H₂ (Ethylene)**
- Each carbon has 1 sigma bond with hydrogen and 1 sigma bond with the other carbon.
- Steric number = 2 (2 sigma bonds + 0 lone pairs).
- Hybridization = sp.
- Structure = Linear.

**Option D: C₂H₄ (Ethylene)**
- Each carbon has 2 sigma bonds with hydrogen and 1 sigma bond with the other carbon.
- Steric number = 3 (3 sigma bonds + 0 lone pairs).
- Hybridization = sp².
- Structure = Trigonal planar (not linear).

3. **Conclusion**:
- The only compound with a linear structure is **C₂H₂**.

### Final Answer:
The compound with a linear structure is **C₂H₂**.