In order to explain the characteristic geometrical shapes of polyatomic molecules, Pauling introduced the concept of hybridisation. The orbitals undergoing hybridisation should have nearly same energy. There are various types of hybridisations involving s, p and d - type of orbitals. The type of hybridisation gives the characteristic shape of the molecular or ion.
Which of the following molecule/ion does not have same number of lone pairs?

Options

A. `SF_(4)`
B. `PH_(3)`
C. `ClO_(3)^(-)`
D. `XeF_(2)`

Explanation

To determine which molecule or ion does not have the same number of lone pairs on the central atom, we will analyze the hybridization and lone pairs of each given molecule/ion.

### Step-by-Step Solution:

1. **Identify the Molecules/Ions**: We need to analyze the following molecules/ions: SF4, PH3, ClO3^-, and XeF2.

2. **Determine Valence Electrons**:
- **SF4 (Sulfur Tetrafluoride)**:
- Sulfur has 6 valence electrons.
- 4 fluorine atoms contribute 4 electrons.
- Total = 6 + 4 = 10 electrons.

- **PH3 (Phosphine)**:
- Phosphorus has 5 valence electrons.
- 3 hydrogen atoms contribute 3 electrons.
- Total = 5 + 3 = 8 electrons.

- **ClO3^- (Chlorate Ion)**:
- Chlorine has 7 valence electrons.
- 3 oxygen atoms contribute 3 electrons.
- The negative charge adds 1 electron.
- Total = 7 + 3 + 1 = 11 electrons.

- **XeF2 (Xenon Difluoride)**:
- Xenon has 8 valence electrons.
- 2 fluorine atoms contribute 2 electrons.
- Total = 8 + 2 = 10 electrons.

3. **Calculate Hybridization**:
- **SF4**:
- Hybridization = 1/2 * (10) = 5 (sp3d).
- Lone pairs = 1 (4 bond pairs + 1 lone pair).

- **PH3**:
- Hybridization = 1/2 * (8) = 4 (sp3).
- Lone pairs = 1 (3 bond pairs + 1 lone pair).

- **ClO3^-**:
- Hybridization = 1/2 * (11) = 4 (sp3).
- Lone pairs = 1 (3 bond pairs + 1 lone pair).

- **XeF2**:
- Hybridization = 1/2 * (10) = 5 (sp3d).
- Lone pairs = 3 (2 bond pairs + 3 lone pairs).

4. **Compare Lone Pairs**:
- SF4: 1 lone pair
- PH3: 1 lone pair
- ClO3^-: 1 lone pair
- XeF2: 3 lone pairs

5. **Conclusion**: The molecule that does not have the same number of lone pairs as the others is **XeF2**, which has 3 lone pairs, while the others have only 1 lone pair.

### Final Answer:
**XeF2 does not have the same number of lone pairs as the other molecules.**