To answer the question "MgO is used for lining furnaces because:", we will break down the reasoning step by step.
### Step-by-Step Solution:
1. **Understanding the Material**:
- Magnesium Oxide (MgO) is a compound formed from magnesium and oxygen.
**Hint**: Consider the composition of MgO and its basic properties.
2. **Properties of MgO**:
- One of the key properties of MgO is its high melting point, which is approximately 2,500 to 2,800 degrees Celsius.
**Hint**: Think about how the melting point of a material affects its use in high-temperature environments.
3. **Application in Furnaces**:
- Furnaces operate at very high temperatures, especially in processes like metal smelting and refining. Materials used for lining must withstand these extreme conditions without melting or degrading.
**Hint**: Reflect on the conditions inside a furnace and what materials would be suitable for such an environment.
4. **Resistance to Heat**:
- MgO not only has a high melting point but is also resistant to thermal shock, meaning it can handle rapid temperature changes without cracking or breaking.
**Hint**: Consider the importance of thermal stability in materials used in construction and lining of furnaces.
5. **Conclusion**:
- Therefore, the primary reason MgO is used for lining furnaces is due to its high melting point and its ability to withstand extreme heat without losing structural integrity.
**Hint**: Summarize the key properties that make MgO suitable for high-temperature applications.
### Final Answer:
MgO is used for lining furnaces because it has a high melting point (approximately 2,500 to 2,800 degrees Celsius) and is resistant to heat, making it ideal for withstanding the extreme temperatures found in furnaces.
