Define the following terms:
(i) Roasting
(ii) Calcination

Explanation

### Step-by-Step Text Solution

#### (i) Roasting
Roasting is a metallurgical process used for the extraction of metals from their ores. It involves heating the concentrated ore in the presence of oxygen (or air). The main purpose of roasting is to convert the ore into a more chemically reactive form, often resulting in the formation of metal oxides and the release of gaseous by-products.

For example, when zinc sulfide (ZnS) is roasted, it reacts with oxygen to produce zinc oxide (ZnO) and sulfur dioxide (SO2):
\[ \text{2ZnS} + \text{3O}_2 \rightarrow \text{2ZnO} + \text{2SO}_2 \]

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