Which of the following is/are pyroscilicate?

Options

A. `Sc_(2)Si_(2)O_(7)`
B. `Mg_2SiO_(4)`
C. `Ca_(3)Si_(3)O_(9)`
D. `Zn_(2)SiO_(4)`

Explanation

To determine which of the given compounds is a pyrosilicate, we need to understand the structure and characteristics of pyrosilicates.

### Step-by-Step Solution:

1. **Understanding Pyrosilicates**:
- Pyrosilicates are silicates that consist of two SiO4 tetrahedra sharing one oxygen atom. This results in the formation of the anion Si2O7^6-.

2. **Analyzing the Given Options**:
- We have three compounds to analyze:
- **(a) Sc2Si2O7**
- **(b) Mg2SiO4**
- **(c) Ca3Si3O9**

3. **Evaluating Each Compound**:
- **(a) Sc2Si2O7**:
- This compound can be broken down into the anion Si2O7^6-.
- Since it contains the pyrosilicate structure (two SiO4 tetrahedra sharing one oxygen), this is indeed a pyrosilicate.

- **(b) Mg2SiO4**:
- This compound consists of the anion SiO4^4-.
- It does not have the pyrosilicate structure, as it represents an orthosilicate (where the SiO4 tetrahedra are discrete and not sharing any oxygen).

- **(c) Ca3Si3O9**:
- This compound can be represented as Si3O9^6-.
- This does not fit the definition of a pyrosilicate either, as it does not have the Si2O7^6- structure. It is more complex and can be classified under other silicate structures.

4. **Conclusion**:
- The only compound that qualifies as a pyrosilicate is **Sc2Si2O7**.
- Therefore, the answer is option **(a) Sc2Si2O7**.