Glass and cement are two important examples of

Options

A. man-made silicates
B. silicons
C. zeolites
D. organic polymers

Answer

To answer the question "Glass and cement are two important examples of," we will analyze the components and characteristics of both materials step by step.

### Step-by-Step Solution:

1. **Understanding Glass**:
- Glass is primarily made from a mixture of metallic silicates, which include compounds of sodium, potassium, calcium, and sometimes lead.
- The process of making glass involves fusing these silicates at high temperatures to form a transparent, solid material.

2. **Understanding Cement**:
- Cement is a fine powder that, when mixed with water and aggregates (like sand and gravel), hardens to form concrete.
- The main components of cement include silicate minerals, which are derived from various natural materials like rocks and clay. A common formula for a component of cement is 2CaO.SiO2 (di-calcium silicate), which also contains silicate.

3. **Identifying the Commonality**:
- Both glass and cement are made from silicates. Silicates are compounds that contain silicon and oxygen, and they are a major component of the Earth's crust.
- Both materials require a process of mixing and heating (for glass) or mixing with water (for cement) to achieve their final forms.

4. **Conclusion**:
- Since both glass and cement are derived from silicate materials and involve human intervention in their production, they can be categorized as "man-made silicates."

Thus, the correct answer to the question is that glass and cement are two important examples of **man-made silicates**.