Main ore of lead is gaalena.This is mined and separated from other minerals by froth flotation.There are two methods of extracting the lead.
(i)First method involves the roasting of ore followed by
reduction with coke or CO.
(ii)Second method involves the partial roasting of ore followed by
self reduction.
Which of the following statement is incorrect about the extraction of lead from galena ?

Options

A. Galena is a sulphide ore and therefore , it is concentrated by froth flotation process
B. Self reduction takes place in absence of air
C. Complete roasting of galena gives PbO which is then reduced
by coke or CO to give metallic lead
D. `FeSiO_3` is obtained as slag.

Explanation

To determine which statement is incorrect about the extraction of lead from galena (PbS), we need to analyze the provided methods of extraction and the statements regarding them.

### Step-by-Step Solution:

1. **Identify the Ore and Its Concentration Method**:
- The main ore of lead is galena (PbS).
- Galena is concentrated by the froth flotation method, which is suitable for sulfide ores.

2. **Understand the Extraction Methods**:
- **First Method**: This involves roasting the ore followed by reduction with coke or carbon monoxide (CO).
- Roasting converts PbS to PbO:
\[ 2 \text{PbS} + 3 \text{O}_2 \rightarrow 2 \text{PbO} + 2 \text{SO}_2 \]
- Then, PbO is reduced to lead (Pb) using coke or CO:
\[ \text{PbO} + \text{C} \rightarrow \text{Pb} + \text{CO} \]

- **Second Method**: This involves partial roasting of the ore followed by self-reduction.
- Partial roasting also produces PbO and SO2:
\[ 2 \text{PbS} + 3 \text{O}_2 \rightarrow 2 \text{PbO} + 2 \text{SO}_2 \]
- The self-reduction occurs when PbO reacts with unreacted PbS:
\[ 2 \text{PbO} + \text{PbS} \rightarrow 3 \text{Pb} + \text{SO}_2 \]

3. **Evaluate Each Statement**:
- **Statement 1**: "Galena is a sulfide ore and is concentrated by froth flotation."
- This statement is **correct**.
- **Statement 2**: "Self-reduction takes place in the absence of air."
- This statement is **correct** as self-reduction occurs without additional oxidizing agents.
- **Statement 3**: "Complete roasting of galena gives PbO which is then reduced."
- This statement is **correct** as it accurately describes the roasting and reduction process.
- **Statement 4**: "FeSiO3 is obtained as the slag."
- This statement is **incorrect**. FeSiO3 (silicate slag) is typically associated with the extraction of copper, not lead.

4. **Conclusion**:
- The incorrect statement about the extraction of lead from galena is **Statement 4**.

### Final Answer:
The incorrect statement about the extraction of lead from galena is: **"FeSiO3 is obtained as the slag."**

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