Neutral refractory material used in furnaces is :

Options

A. Graphite
B. CaO
C. SiO
D. MgO

Answer

To determine the neutral refractory material used in furnaces, we need to analyze the options provided and understand the characteristics of different types of refractory materials.

### Step-by-Step Solution:

1. **Understanding Refractory Materials**:
Refractory materials are those that can withstand high temperatures without melting or deforming. They are classified into three categories: acidic, basic, and neutral.

2. **Defining Neutral Refractory Materials**:
Neutral refractory materials are those that do not react with either acidic or basic environments. They are used in situations where the furnace atmosphere can be either acidic or basic.

3. **Analyzing the Options**:
- **Option A: Graphite**: Graphite is known to be a neutral refractory material. It does not react with acidic or basic environments, making it suitable for use in furnaces where both conditions may be present.
- **Option B: Calcium Oxide**: Calcium oxide is a basic refractory material. It is used in basic environments and will react with acidic materials, so it is not neutral.
- **Option C: Silicon Oxide (Silica)**: Silicon oxide is an acidic refractory material. It is used in acidic environments and will react with basic materials, so it is also not neutral.
- **Option D: Magnesium Oxide**: Magnesium oxide is another basic refractory material. Like calcium oxide, it is used in basic environments and will react with acidic materials, making it not neutral.

4. **Conclusion**:
Based on the analysis, the only neutral refractory material listed among the options is **Graphite** (Option A). Therefore, the correct answer is:

**Neutral refractory material used in furnaces is: Graphite (Option A).**