The silicate anion in the mineral kinoite is a chain of three `SiO_(4)` tetrahedra, that share corners with adjacent tetrahedra. The charge pof silicate anion is

Options

A. `-4`
B. `-8`
C. `-6`
D. `-2`

Answer

To determine the charge of the silicate anion in the mineral kinoite, we need to analyze the structure of the silicate anion formed by three SiO₄ tetrahedra.

### Step-by-Step Solution:

1. **Understanding the Tetrahedra Structure**:
Each SiO₄ tetrahedron consists of one silicon atom (Si) surrounded by four oxygen atoms (O). The silicon atom has a +4 charge, while each oxygen atom has a -2 charge.

2. **Calculating the Charge of One Tetrahedron**:
- Charge from silicon: +4
- Charge from four oxygen atoms: 4 × (-2) = -8
- Total charge of one SiO₄ tetrahedron = +4 + (-8) = -4

3. **Analyzing the Chain of Tetrahedra**:
In the case of kinoite, there are three SiO₄ tetrahedra linked together in a chain. When tetrahedra share corners, they do not contribute additional negative charges from the shared oxygen atoms.

4. **Calculating the Total Charge for Three Tetrahedra**:
- Total charge from three tetrahedra = 3 × (-4) = -12

5. **Considering Shared Oxygen Atoms**:
When three tetrahedra are linked, some oxygen atoms are shared. In this case, we need to determine how many oxygen atoms are effectively contributing to the total charge.
- Each tetrahedron shares oxygen atoms with adjacent tetrahedra. In a chain of three tetrahedra, there are 2 shared oxygen atoms (one between the first and second tetrahedra, and another between the second and third).
- Therefore, the total number of unique oxygen atoms = 12 (from three tetrahedra) - 2 (shared) = 10.

6. **Final Charge Calculation**:
- Total charge from silicon: 3 × (+4) = +12
- Total charge from oxygen: 10 × (-2) = -20
- Overall charge of the silicate anion = +12 + (-20) = -8

7. **Conclusion**:
The charge of the silicate anion in kinoite is -8.

### Final Answer:
The charge of the silicate anion is -8.