In which of the following change in hybridisation is taking place ?

Options

A. `BF_(3)+NH_(3) to [H_(3)N to BF_(3)]`
B. `NH_(3)+H^(+) to NH_(4)^(+)`
C. `SbF_(5)+F^(-) to [SbF_(6)]^(-)`
D. `2HClO_(2) to HClO+HClO_(3)`

Explanation

To determine in which of the given options a change in hybridization is taking place, we will analyze each option step by step.

### Step 1: Analyze Option A (BF3 + NH3)
1. **Initial Hybridization of BF3**:
- BF3 has 3 sigma bonds and no lone pairs.
- The hybridization is **sp²** (3 orbitals).

2. **After Reaction with NH3**:
- When BF3 reacts with NH3, a bond is formed between B and N.
- Now, BF3 has 4 sigma bonds (3 from BF3 and 1 from NH3).
- The new hybridization becomes **sp³** (4 orbitals).

3. **Change in Hybridization**:
- From **sp²** to **sp³**.

### Step 2: Analyze Option B (NH3 + H+)
1. **Initial Hybridization of NH3**:
- NH3 has 3 sigma bonds and 1 lone pair.
- The hybridization is **sp³** (4 orbitals).

2. **After Reaction with H+**:
- NH3 forms NH4+, which has 4 sigma bonds and no lone pairs.
- The hybridization remains **sp³** (4 orbitals).

3. **Change in Hybridization**:
- No change (remains **sp³**).

### Step 3: Analyze Option C (SbF5 + F-)
1. **Initial Hybridization of SbF5**:
- SbF5 has 5 sigma bonds and no lone pairs.
- The hybridization is **sp³d** (5 orbitals).

2. **After Reaction with F-**:
- When SbF5 reacts with F-, it forms SbF6-.
- Now, SbF6- has 6 sigma bonds.
- The new hybridization becomes **sp³d²** (6 orbitals).

3. **Change in Hybridization**:
- From **sp³d** to **sp³d²**.

### Step 4: Analyze Option D (HClO2)
1. **Initial Hybridization of HClO2**:
- HClO2 has 3 sigma bonds and 1 lone pair on Cl.
- The hybridization is **sp³** (4 orbitals).

2. **After Reaction**:
- HClO2 can form HClO and HClO3.
- The hybridization of Cl in both products remains **sp³**.

3. **Change in Hybridization**:
- No change (remains **sp³**).

### Conclusion:
- The options where a change in hybridization occurs are:
- **Option A**: from **sp²** to **sp³**.
- **Option C**: from **sp³d** to **sp³d²**.

### Final Answer:
The correct options indicating a change in hybridization are **A and C**.

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