The solid compound `SiO_(2)` exist in the forms of

Options

A. crystalline in quartz
B. amorphous in quartz
C. amorphous in silica glass
D. crystalline in silica glass

Answer

To answer the question regarding the forms in which the solid compound SiO₂ (silicon dioxide) exists, we can break down the solution into a few clear steps:

### Step-by-Step Solution:

1. **Understanding SiO₂**:
- Silicon dioxide (SiO₂) is a compound that can exist in different structural forms. It is commonly found in nature and has significant applications in various fields.

2. **Crystalline Form - Quartz**:
- One of the most well-known crystalline forms of SiO₂ is quartz. Quartz has a well-defined, ordered structure where the silicon and oxygen atoms are arranged in a repeating pattern. This regular arrangement gives quartz its characteristic properties, such as hardness and a specific melting point.

3. **Properties of Crystalline Quartz**:
- Quartz is a tough solid and does not flow. The atoms in quartz are arranged in a regular pattern, which contributes to its stability and rigidity.

4. **Amorphous Form - Silica Glass**:
- In contrast to quartz, SiO₂ can also exist in an amorphous form known as silica glass. Unlike quartz, silica glass does not have a long-range order in its atomic arrangement.

5. **Properties of Amorphous Silica Glass**:
- Silica glass is often described as a supercooled liquid because it can flow over time, albeit very slowly. It lacks the regular repeating pattern found in crystalline solids, which gives it different physical properties, such as transparency and flexibility.

6. **Conclusion**:
- Therefore, SiO₂ exists in two main forms:
- Crystalline form (as in quartz)
- Amorphous form (as in silica glass)

### Final Answer:
The solid compound SiO₂ exists in the forms of crystalline (as quartz) and amorphous (as silica glass).

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