Which molecule does not exist ?

Options

A. `OF_(2)`
B. `OF_(4)`
C. `SF_(2)`
D. `SF_(4)`

Explanation

To determine which molecule does not exist, we will analyze the bonding capabilities of the central atoms involved in the given molecules.

### Step-by-Step Solution:

1. **Identify the Central Atoms**:
- We have oxygen (O) and sulfur (S) as central atoms in the given molecules.

2. **Determine Valence Electrons**:
- For oxygen (atomic number 8):
- Electron configuration: 1s² 2s² 2p⁴
- Valence electrons: 6 (2 from 2s and 4 from 2p)
- For sulfur (atomic number 16):
- Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁴
- Valence electrons: 6 (2 from 3s and 4 from 3p)

3. **Calculate Maximum Covalency**:
- Oxygen can form a maximum of 2 bonds because it does not have available d-orbitals in the second period.
- Sulfur can form more bonds due to the availability of d-orbitals in the third period, allowing it to have a maximum covalency of 6.

4. **Analyze Given Molecules**:
- **OF₂**: Oxygen can form 2 bonds with fluorine. This molecule exists.
- **OF₄**: Oxygen can only form 2 bonds. This molecule does not exist.
- **SF₂**: Sulfur can form 2 bonds with fluorine. This molecule exists.
- **SF₄**: Sulfur can form 4 bonds with fluorine due to the availability of d-orbitals. This molecule exists.

5. **Conclusion**:
- The molecule that does not exist is **OF₄** because oxygen cannot exceed its maximum covalency of 2.

### Summary:
The molecule that does not exist is **OF₄**.