(vi) In Bessenmerisation of sulphide ore of copper, there is self-reduction giving copper metal.

Explanation

### Step-by-Step Solution:

1. **Understanding Bessemerisation**:
Bessemerisation is a process used to extract metals from their ores, particularly for copper from its sulphide ores. The process involves the oxidation of the sulphide ore to produce metal.

**Hint**: Remember that Bessemerisation is primarily used for extracting metals from their ores through oxidation.

2. **Chemical Reaction**:
The primary reaction involved in the Bessemerisation of copper sulphide (CuS) is:
\[ 2 \text{CuS} + 3 \text{O}_2 \rightarrow 2 \text{Cu}_2\text{O} + 2 \text{SO}_2 \]
In this reaction, copper(I) oxide (Cu2O) and sulfur dioxide (SO2) are produced.

**Hint**: Identify the reactants and products in the chemical equation to understand the transformation occurring in the process.

3. **Self-Reduction Process**:
The next step involves the self-reduction of the copper(I) oxide formed. The reaction can be represented as:
\[ 2 \text{Cu}_2\text{O} + \text{Cu}_2\text{S} \rightarrow 6 \text{Cu} + \text{S} \]
Here, the copper(I) oxide is reduced back to copper metal while the copper sulphide is oxidized to sulfur.

**Hint**: Look for how the products of the first reaction are utilized in the second reaction, showcasing the self-reduction aspect.

4. **Final Outcome**:
The overall process results in the extraction of copper metal from its sulphide ore through a series of oxidation and reduction reactions, demonstrating the concept of self-reduction.

**Hint**: Summarize the entire process to see how the initial ore is transformed into pure metal.

5. **Conclusion**:
Bessemerisation of copper sulphide ore is an effective method for obtaining copper metal, highlighting the self-reduction mechanism where the ore reduces itself to yield the metal.

**Hint**: Reflect on the significance of self-reduction in metallurgical processes, especially in the context of copper extraction.