The state of hybridization of the central atom is not the same as in the others :

Options

A. B in `BF_(3)`
B. O in `H_(3)O^(+)`
C. N in `NH_(3)`
D. P in `PCl_(3)`

Answer

To determine which molecule has a different state of hybridization compared to the others, we will analyze the hybridization of the central atom in each of the four given molecules: BF3, SO3^2-, NH3, and PCl3.

### Step-by-Step Solution:

1. **Identify the Central Atom and Valence Electrons**:
- **BF3**: The central atom is Boron (B). Boron has 3 valence electrons.
- **SO3^2-**: The central atom is Sulfur (S). Sulfur has 6 valence electrons.
- **NH3**: The central atom is Nitrogen (N). Nitrogen has 5 valence electrons.
- **PCl3**: The central atom is Phosphorus (P). Phosphorus has 5 valence electrons.

2. **Determine Bond Pairs and Lone Pairs**:
- **BF3**: Boron forms 3 bond pairs with 3 fluorine atoms and has 0 lone pairs.
- **SO3^2-**: Sulfur forms 2 bond pairs with oxygen atoms and has 2 lone pairs.
- **NH3**: Nitrogen forms 3 bond pairs with hydrogen atoms and has 1 lone pair.
- **PCl3**: Phosphorus forms 3 bond pairs with chlorine atoms and has 1 lone pair.

3. **Calculate Hybridization**:
- **BF3**: Hybridization = Number of bond pairs + Number of lone pairs = 3 + 0 = **sp²**.
- **SO3^2-**: Hybridization = 2 + 2 = **sp³**.
- **NH3**: Hybridization = 3 + 1 = **sp³**.
- **PCl3**: Hybridization = 3 + 1 = **sp³**.

4. **Compare Hybridizations**:
- BF3 has a hybridization of **sp²**.
- SO3^2-, NH3, and PCl3 all have a hybridization of **sp³**.

5. **Conclusion**:
- The molecule with a different hybridization state is **BF3**, as it has sp² hybridization while the others have sp³ hybridization.

### Final Answer:
The state of hybridization of the central atom in BF3 is different from the others (SO3^2-, NH3, and PCl3) because BF3 has sp² hybridization while the others have sp³ hybridization.

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