Electric furnaces are lined with magnesia because

Options

A. It melts at a very high temperature
B. It is not affected by acids
C. It has no effect of electricity
D. It liberated oxygen on heating

Explanation

**Step-by-Step Solution:**

1. **Understanding the Function of Electric Furnaces:**
- Electric furnaces are used for various high-temperature processes, including melting metals and other materials.

2. **Material Selection for Lining:**
- The lining material of an electric furnace must be able to withstand extreme temperatures without melting or degrading.

3. **Properties of Magnesia:**
- Magnesia, chemically known as magnesium oxide (MgO), is known for its high melting point, which is around 2800°C (5072°F). This makes it suitable for high-temperature applications.

4. **Reason for Using Magnesia:**
- Because of its high melting point, magnesia can endure the intense heat generated within electric furnaces without melting or losing structural integrity. This property allows the furnace to operate efficiently at high temperatures.

5. **Conclusion:**
- Therefore, electric furnaces are lined with magnesia to ensure they can withstand the high temperatures necessary for their operation.

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