How is mercury extracted from its sulphide ore? Write the balanced chemical equations involved in the process.
Why are carbonate or sulphide ores converted to oxides during the process of extraction?
Is magnesium oxide an ionic compound or a covalent compound? Give reasons to support your answer.

Explanation

### Step-by-Step Solution:

**1. Extraction of Mercury from its Sulphide Ore:**
- The sulphide ore of mercury is known as Cinnabar, which has the chemical formula HgS (mercury(II) sulfide).
- To extract mercury, Cinnabar is heated in the presence of oxygen. The reaction can be represented as follows:

**Chemical Equation:**
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