The basis building unit of silicates is `"………….."` .

Answer

To determine the basic building unit of silicates, we need to analyze the composition and structure of silicates.

### Step-by-Step Solution:

1. **Understanding Silicates**:
- Silicates are compounds that contain silicon (Si) and oxygen (O) as their primary components. They are one of the most abundant groups of minerals in the Earth's crust.

2. **Identifying the Basic Unit**:
- The fundamental building block of silicates is the **silicate tetrahedron**. This tetrahedron consists of one silicon atom surrounded by four oxygen atoms.

3. **Chemical Formula**:
- The chemical formula for the silicate tetrahedron is represented as **SiO₄⁴⁻**. This indicates that the tetrahedron carries a -4 charge due to the four oxygen atoms.

4. **Structure of Silicates**:
- These tetrahedra can link together in various ways to form different silicate structures, such as chains, sheets, or three-dimensional frameworks. The connectivity of these tetrahedra is what gives rise to the diversity of silicate minerals.

5. **Conclusion**:
- Therefore, the basic building unit of silicates is the **silicate tetrahedron (SiO₄⁴⁻)**.

### Final Answer:
The basic building unit of silicates is **SiO₄⁴⁻**.

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