Flux used in the smelting of copper arc is:

Options

A. coke
B. magnesia
C. silica
D. lime stone

Answer

To answer the question regarding the flux used in the smelting of copper, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Smelting**:
- Smelting is a process that involves heating ores to extract a base metal. It typically involves the application of heat and the use of a flux to facilitate the separation of metal from its ore.

2. **Role of Flux**:
- A flux is a substance added during the smelting process to help remove impurities from the metal. It combines with the impurities to form a slag, which can be easily removed.

3. **Identifying the Flux for Copper**:
- In the smelting of copper, one of the common fluxes used is silica (SiO2). Silica reacts with the impurities present in the copper ore, such as iron oxides.

4. **Chemical Reaction**:
- The reaction can be represented as follows:
\[ \text{FeO} + \text{SiO}_2 \rightarrow \text{FeSiO}_3 \]
- Here, iron oxide (FeO) reacts with silica to form iron silicate (FeSiO3), which is the slag that can be removed.

5. **Conclusion**:
- Therefore, the flux used in the smelting of copper is silica.

### Final Answer:
The flux used in the smelting of copper is **silica**.

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