Which of the following does not have `sp^3` hybridisation ?

Options

A. `BF_4^(-)`
B. `H_3O^(+)`
C. `OF_2`
D. `BF_3`

Answer

To determine which of the given compounds does not have `sp^3` hybridization, we will analyze each option step by step.

### Step 1: Analyze BF4⁻
- **Valence Electrons**: Boron (B) has 3 valence electrons, and each Fluorine (F) has 7 valence electrons. In BF4⁻, Boron forms 3 bonds with Fluorine and accepts a lone pair from an F⁻ ion.
- **Steric Number Calculation**:
- Number of sigma bonds = 4 (3 from F and 1 from the coordinate bond)
- Number of lone pairs = 0
- Steric number = 4 + 0 = 4
- **Hybridization**: Since the steric number is 4, the hybridization is `sp^3`.

### Step 2: Analyze H3O⁺
- **Valence Electrons**: Oxygen (O) has 6 valence electrons. In H3O⁺, it forms 3 bonds with Hydrogen (H) and has one lone pair.
- **Steric Number Calculation**:
- Number of sigma bonds = 3
- Number of lone pairs = 1
- Steric number = 3 + 1 = 4
- **Hybridization**: Since the steric number is 4, the hybridization is `sp^3`.

### Step 3: Analyze OF2
- **Valence Electrons**: Oxygen (O) has 6 valence electrons. In OF2, it forms 2 bonds with Fluorine and has 2 lone pairs.
- **Steric Number Calculation**:
- Number of sigma bonds = 2
- Number of lone pairs = 2
- Steric number = 2 + 2 = 4
- **Hybridization**: Since the steric number is 4, the hybridization is `sp^3`.

### Step 4: Analyze BF3
- **Valence Electrons**: Boron (B) has 3 valence electrons. In BF3, it forms 3 bonds with Fluorine and has no lone pairs.
- **Steric Number Calculation**:
- Number of sigma bonds = 3
- Number of lone pairs = 0
- Steric number = 3 + 0 = 3
- **Hybridization**: Since the steric number is 3, the hybridization is `sp^2`.

### Conclusion
Among the given options, **BF3** does not have `sp^3` hybridization.

### Summary of Steps:
1. Analyze the valence electrons and bonding in each compound.
2. Calculate the steric number using the formula: Steric number = Number of sigma bonds + Number of lone pairs.
3. Determine the hybridization based on the steric number.