Silica is added to the sulphide ore of copper in reverberatory furnace because

Options

A. 1. sulphide ore of copper contains iron as impurity which is removed as iron slag.
B. 2. silica reacts with `Cu_(2)O` to form slag
C. 3. silica helps in reduction of `Cu_(2)O ` to Cu
D. 4. sulphide ore of copper is separated from iron by reacting with silica.

Explanation

### Step-by-Step Solution:

1. **Understanding the Process**: The question asks why silica is added to the sulphide ore of copper in a reverberatory furnace. To answer this, we first need to understand the process of roasting and the role of silica.

2. **Roasting of Copper Sulphide**: Roasting is a process that involves heating the ore in the presence of oxygen. In this case, copper sulphide (Cu₂S) is roasted to convert it into copper oxide (Cu₂O) and sulfur dioxide (SO₂). The reaction can be represented as:
\[ 2 \text{Cu}_2\text{S} + 3 \text{O}_2 \rightarrow 2 \text{Cu}_2\text{O} + 2 \text{SO}_2 \]

3. **Formation of Slag**: During the roasting process, impurities such as iron are present in the copper sulphide ore. When silica (SiO₂) is added, it reacts with the iron impurities (Fe) to form iron silicate (FeSiO₃), which is known as slag. The reaction can be represented as:
\[ \text{Fe} + \text{SiO}_2 \rightarrow \text{FeSiO}_3 \]

4. **Separation of Impurities**: The formation of slag (FeSiO₃) allows for the separation of iron from the copper ore. The slag is less dense and can be removed easily from the furnace, thus purifying the copper.

5. **Conclusion**: Therefore, silica is added to the sulphide ore of copper in a reverberatory furnace primarily to remove iron impurities as iron slag.

### Final Answer:
Silica is added to the sulphide ore of copper in a reverberatory furnace to remove iron impurities by forming iron silicate (FeSiO₃), which can be separated as slag.

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