Which of the following pairs have same hybridisation ?

Options

A. `CH_(3)^(-)` and `CH_(3)^(+)`
B. `NH_(3)` and `SO_(2)`
C. `SO_(4)^(2-)` and `BF_(4)^(-)`
D. `BF_(3)` and `NF_(3)`

Answer

To determine which pairs of molecules have the same hybridization, we need to analyze the hybridization of each molecule in the given pairs.

### Step-by-Step Solution:

1. **Identify the Valence Electrons:**
- For each molecule, we first need to determine the number of valence electrons based on the constituent atoms.

2. **Determine the Hybridization:**
- Use the formula:
\[ \text{Hybridization} = \text{Number of Sigma Bonds} + \text{Number of Lone Pairs} \]
- The hybridization types correspond to the following:
- 2 = sp
- 3 = sp²
- 4 = sp³
- 5 = sp³d
- 6 = sp³d²

3. **Analyze Each Pair:**
- **Pair A: CS3 and C2H6**
- **CS3:** Carbon has 4 valence electrons and forms 3 sigma bonds with hydrogen and has no lone pairs. So, hybridization = 3 (sigma bonds) + 0 (lone pairs) = sp².
- **C2H6:** Each carbon forms 4 sigma bonds (3 with hydrogens and 1 with another carbon). So, hybridization = 4 (sigma bonds) + 0 (lone pairs) = sp³.
- **Conclusion:** Different hybridizations.

- **Pair B: NH3 and SO2**
- **NH3:** Nitrogen has 5 valence electrons, forms 3 sigma bonds with hydrogen and has 1 lone pair. So, hybridization = 3 + 1 = sp³.
- **SO2:** Sulfur has 6 valence electrons, forms 2 double bonds with oxygen (2 sigma bonds) and has 1 lone pair. So, hybridization = 2 + 1 = sp².
- **Conclusion:** Different hybridizations.

- **Pair C: SO4²- and BF4-**
- **SO4²-:** Sulfur has 6 valence electrons, forms 4 sigma bonds with oxygen and has no lone pairs. So, hybridization = 4 + 0 = sp³.
- **BF4-:** Boron has 3 valence electrons, forms 4 sigma bonds with fluorine and has no lone pairs. So, hybridization = 4 + 0 = sp³.
- **Conclusion:** Same hybridizations.

- **Pair D: BF3 and NF3**
- **BF3:** Boron has 3 valence electrons, forms 3 sigma bonds with fluorine and has no lone pairs. So, hybridization = 3 + 0 = sp².
- **NF3:** Nitrogen has 5 valence electrons, forms 3 sigma bonds with fluorine and has 1 lone pair. So, hybridization = 3 + 1 = sp³.
- **Conclusion:** Different hybridizations.

### Final Answer:
The pair that has the same hybridization is **SO4²- and BF4-**.