(xii) Which is known as 'blister copper' ?

Options

A. Pure copper
B. `98 %` copper
C. Alloy of copper
D. Ore of copper

Answer

**Step-by-Step Text Solution:**

1. **Understanding the term 'blister copper':** Blister copper refers to a specific form of copper that is produced during the smelting process.

2. **Purity of blister copper:** Blister copper is typically around 97% to 98% pure. This level of purity is significant in the context of copper production.

3. **Formation process:** The blister copper is formed through a smelting process, which involves heating copper ores to extract the metal.

4. **Appearance of blister copper:** The name 'blister copper' comes from its characteristic blistery surface. This appearance is due to the evolution of sulfur dioxide (SO2) gas during the smelting process.

5. **Conclusion:** Therefore, blister copper is defined as copper that is produced by smelting and has a purity of about 97% to 98%, characterized by its blistered surface caused by the release of SO2 gas.

**Final Answer:** Blister copper is known as copper that is 97% to 98% pure, produced by the smelting process, and has a blistery surface due to the evolution of sulfur dioxide gas.

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