Which of the following sets of molecules contains the same number of lone pairs of electrons in the central atom ?

Options

A. `SO_(2),ClF_(3),BrF_(3)`
B. `SF_(4),NH_(3),O_(3)`
C. `ClF_(3),XeF_(2),H_(2)O`
D. `H_(2)O,SF_(2),NH_(3)`

Explanation

To determine which set of molecules contains the same number of lone pairs of electrons on the central atom, we will analyze each molecule step by step.

### Step-by-Step Solution:

1. **Identify the Molecules**: We will analyze the following molecules:
- SO2 (sulfur dioxide)
- ClF3 (chlorine trifluoride)
- BrF3 (bromine trifluoride)
- SF4 (sulfur tetrafluoride)
- NH3 (ammonia)
- O3 (ozone)
- XeF2 (xenon difluoride)
- H2O (water)
- SF2 (sulfur difluoride)

2. **Calculate Lone Pairs for Each Molecule**:
- **SO2**:
- Central atom: Sulfur (S)
- Valence electrons: 6 (S) + 2 (O) × 2 = 10
- Bond pairs: 2 (S=O bonds)
- Lone pairs: 6 - 2 = 4 electrons left, which means 1 lone pair (4/2 = 2 pairs).

- **ClF3**:
- Central atom: Chlorine (Cl)
- Valence electrons: 7 (Cl) + 3 (F) × 1 = 10
- Bond pairs: 3 (Cl-F bonds)
- Lone pairs: 7 - 3 = 4 electrons left, which means 2 lone pairs (4/2 = 2 pairs).

- **BrF3**:
- Central atom: Bromine (Br)
- Valence electrons: 7 (Br) + 3 (F) × 1 = 10
- Bond pairs: 3 (Br-F bonds)
- Lone pairs: 7 - 3 = 4 electrons left, which means 2 lone pairs (4/2 = 2 pairs).

- **SF4**:
- Central atom: Sulfur (S)
- Valence electrons: 6 (S) + 4 (F) × 1 = 10
- Bond pairs: 4 (S-F bonds)
- Lone pairs: 6 - 4 = 2 electrons left, which means 1 lone pair (2/2 = 1 pair).

- **NH3**:
- Central atom: Nitrogen (N)
- Valence electrons: 5 (N) + 3 (H) × 1 = 8
- Bond pairs: 3 (N-H bonds)
- Lone pairs: 5 - 3 = 2 electrons left, which means 1 lone pair (2/2 = 1 pair).

- **O3**:
- Central atom: Oxygen (O)
- Valence electrons: 6 (O) + 2 (O) × 1 = 8
- Bond pairs: 2 (O=O bonds)
- Lone pairs: 6 - 4 = 2 electrons left, which means 1 lone pair (2/2 = 1 pair).

- **XeF2**:
- Central atom: Xenon (Xe)
- Valence electrons: 8 (Xe) + 2 (F) × 1 = 10
- Bond pairs: 2 (Xe-F bonds)
- Lone pairs: 8 - 4 = 4 electrons left, which means 2 lone pairs (4/2 = 2 pairs).

- **H2O**:
- Central atom: Oxygen (O)
- Valence electrons: 6 (O) + 2 (H) × 1 = 8
- Bond pairs: 2 (O-H bonds)
- Lone pairs: 6 - 4 = 2 electrons left, which means 2 lone pairs (2/2 = 1 pair).

- **SF2**:
- Central atom: Sulfur (S)
- Valence electrons: 6 (S) + 2 (F) × 1 = 8
- Bond pairs: 2 (S-F bonds)
- Lone pairs: 6 - 4 = 2 electrons left, which means 2 lone pairs (2/2 = 1 pair).

3. **Summary of Lone Pairs**:
- SO2: 1 lone pair
- ClF3: 2 lone pairs
- BrF3: 2 lone pairs
- SF4: 1 lone pair
- NH3: 1 lone pair
- O3: 1 lone pair
- XeF2: 3 lone pairs
- H2O: 2 lone pairs
- SF2: 1 lone pair

4. **Identify Sets with the Same Number of Lone Pairs**:
- SO2, SF4, NH3, O3, and SF2 each have **1 lone pair**.
- ClF3, BrF3, H2O each have **2 lone pairs**.

### Conclusion:
The sets of molecules that contain the same number of lone pairs of electrons in the central atom are:
- SO2, SF4, NH3, O3, SF2 (1 lone pair)
- ClF3, BrF3, H2O (2 lone pairs)