Silica is added to roasted copper during extraction in order to remove:

Options

A. cuprous sulphide
B. ferrous oxide
C. ferrous sulphide
D. cuprous oxide

Answer

To solve the question regarding why silica is added to roasted copper during its extraction, we can follow these steps:

### Step 1: Understand the context of copper extraction
In metallurgy, copper is extracted from its ores through processes such as roasting and smelting. During roasting, the ore is heated in the presence of oxygen, which helps convert the metal sulfides into oxides.

**Hint:** Consider the chemical reactions that occur during the roasting process of copper ores.

### Step 2: Identify the impurities in copper ore
Copper ores often contain various impurities, with iron being one of the most common. When copper ores are roasted, the iron present in the ore can form ferrous oxide (FeO).

**Hint:** Think about the common impurities found in copper ores and what happens to them during roasting.

### Step 3: Role of silica in the extraction process
Silica (SiO2) is added to the roasted copper to act as a flux. A flux is a substance that helps to remove impurities from metals during the extraction process. In this case, silica reacts with ferrous oxide to form a slag, which is a waste material that can be easily removed.

**Hint:** Recall what a flux does in metallurgy and how it interacts with impurities.

### Step 4: Chemical reaction
The reaction between silica and ferrous oxide can be represented as follows:
\[ \text{FeO} + \text{SiO}_2 \rightarrow \text{FeSiO}_3 \]
This forms ferrosilicate, which is a slag that can be separated from the molten copper.

**Hint:** Consider writing out the chemical equation to visualize the reaction taking place.

### Step 5: Conclusion
Thus, the primary reason for adding silica to roasted copper during extraction is to remove ferrous oxide, which is formed as a byproduct during the roasting of copper ores.

**Final Answer:** Silica is added to roasted copper during extraction in order to remove ferrous oxide.