Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them? 

Explanation

**Step-by-Step Solution:**

1. **Understanding the Extraction Process**: The extraction of metals from their ores often involves converting metal sulfides and carbonates into metal oxides. This is an essential step in the metallurgical process.

2. **Reason for Conversion**: The primary reason for converting metal sulfides and carbonates to metal oxides is that it simplifies the reduction process. Reduction of metal oxides is generally easier and more efficient than reducing metal sulfides or carbonates directly to the metal.

3. **Processes Involved**:
- **Calcination**: This process is used for carbonate ores. During calcination, the carbonate is heated in the absence of oxygen, leading to the formation of metal oxide and the release of carbon dioxide (CO2).
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