Which of the following anions is present in the chain structure of silicates?

Options

A. `Si_(2)O_(7)^(6-)`
B. `(Si_(2)O_(5)^(2-))_(n)`
C. `(SiO_(3)^(2-))_(n)`
D. `SiO_(4)^(4-)`

Explanation

To determine which anion is present in the chain structure of silicates, we need to analyze the given options and understand the characteristics of silicate structures.

### Step-by-Step Solution:

1. **Understanding Silicate Structures**:
- Silicates can be classified into different structures: isolated tetrahedra, chain silicates, sheet silicates, and framework silicates. Chain silicates are characterized by the sharing of oxygen atoms between silicon tetrahedra.

2. **Analyzing the Options**:
- We have four options to consider:
1. Si2O7^6− (disilicate)
2. Si2O5^2− (sheet silicate)
3. SiO3^2− (chain silicate)
4. SiO4^4− (single tetrahedral unit)

3. **Evaluating Each Option**:
- **Option 1: Si2O7^6−**:
- This represents disilicate, which consists of two silicon tetrahedra sharing one oxygen atom. This structure does not represent chain silicates, so it is incorrect.

- **Option 2: Si2O5^2−**:
- This represents sheet silicates, where silicon tetrahedra are arranged in sheets. This is also not a chain silicate, so it is incorrect.

- **Option 3: SiO3^2−**:
- This represents chain silicates. In this structure, each silicon tetrahedron shares two oxygen atoms with adjacent tetrahedra, forming a continuous chain. This is the correct option.

- **Option 4: SiO4^4−**:
- This represents a single tetrahedral unit. While it is a fundamental building block of silicates, it does not represent a chain structure, so it is incorrect.

4. **Conclusion**:
- The only anion that is present in the chain structure of silicates is **SiO3^2−**.

### Final Answer:
The correct anion present in the chain structure of silicates is **SiO3^2−**.

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