In `SiO_(2)`

Options

A. the coordination number of Si is 4 and that of O is 2
B. the coordination number of Si is 2 and that of O is 4
C. the coordination number Si and that of O are both 2
D. the coordination number of Si and that of O are both 4

Answer

To solve the question regarding the coordination numbers in SiO₂ (silicon dioxide), we will follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of SiO₂**:
- SiO₂ consists of silicon (Si) and oxygen (O) atoms. In its crystalline form, silicon dioxide has a tetrahedral structure where each silicon atom is surrounded by four oxygen atoms.

2. **Drawing the Structure**:
- Visualize or draw the tetrahedral structure. Place the silicon atom at the center and arrange four oxygen atoms around it. Each oxygen atom is bonded to the silicon atom.

3. **Determining the Coordination Number of Silicon**:
- The coordination number of an atom refers to the number of atoms directly bonded to it. In SiO₂, each silicon atom is bonded to four oxygen atoms.
- Therefore, the coordination number of silicon (Si) is **4**.

4. **Determining the Coordination Number of Oxygen**:
- Each oxygen atom in SiO₂ is bonded to two silicon atoms (since each oxygen is shared between two silicon atoms).
- Thus, the coordination number of oxygen (O) is **2**.

5. **Conclusion**:
- Based on the analysis, we conclude that the coordination number of silicon in SiO₂ is **4**, and the coordination number of oxygen is **2**.

### Final Answer:
- The coordination number of silicon in SiO₂ is **4**, and the coordination number of oxygen is **2**.