Read the paragraph carefully and answer the following questions:
Silicon is the second most abundant element occurring in earth crust. It is always found in combined state. It is obtained by reduction of silica and exists in two allotropic forms, i.e. amorphous and crystalline. Amorphous form is obtained by heating dry powdered silica with magnesium. Crystalline form is obtained by heating sand or quartz in a furnace. Silicon is used in manufacturing of certain alloys and polymers such as ferrosilicon, silicon bronze etc.
The compounds of silicon are carborundum, silicone, silicates, glass etc. Silicones are organosilicon polymer and silicates are metal derivatives of silicic acid. While carborundum are obtained by heating mixture of sand, carbon and common salt.
Q The structural unit of silicates is

Options

A. `SiO_(2)`
B. `SiO_(4)^(4-)`
C. `SiO_(2)^(3-)`
D. `SiO_(2)^(2-)`

Answer

To answer the question regarding the structural unit of silicates, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Silicates**:
- Silicates are compounds that contain silicon and oxygen, and they often include metals. They are derived from silicic acid.

2. **Identifying the Structural Unit**:
- The structural unit of silicates is based on the arrangement of silicon and oxygen atoms. The most common structural unit in silicates is the silicate tetrahedron.

3. **Silicate Tetrahedron**:
- The silicate tetrahedron consists of one silicon atom (Si) surrounded by four oxygen atoms (O). This can be represented as SiO₄.

4. **Conclusion**:
- Therefore, the structural unit of silicates is SiO₄.

### Final Answer:
The structural unit of silicates is SiO₄.

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