Identify x,y,z for the following metallurgical process :
metal sulphide `overset(x)rarr` metal oxide `overset(y)rarr` impure metal `overset(z)rarr` pure metal
generally x,y and z are respectively:

Options

A. roasting, smelting, electrolysis
B. roasting, calcination, smelting
C. calcination, auto-reduction, bassermerisation
D. none

Answer

To solve the problem, we need to identify the processes represented by x, y, and z in the metallurgical extraction of a metal from its sulfide ore to pure metal.

### Step-by-Step Solution:

1. **Identify the Process for x (Metal Sulfide to Metal Oxide)**:
- The first step involves converting metal sulfide to metal oxide. This process is known as **roasting**. During roasting, the sulfide ore is heated in the presence of air, leading to the formation of the metal oxide and the release of sulfur dioxide gas.
- **Example Reaction**:
\[ 2 \text{PbS} + 3 \text{O}_2 \rightarrow 2 \text{PbO} + 2 \text{SO}_2 \]
- Therefore, **x = roasting**.

2. **Identify the Process for y (Metal Oxide to Impure Metal)**:
- The next step involves reducing the metal oxide to obtain impure metal. This process is called **smelting**. In smelting, the metal oxide is heated with a reducing agent (commonly carbon or carbon monoxide), which reduces the oxide to the metal.
- **Example Reaction**:
\[ \text{PbO} + \text{C} \rightarrow \text{Pb} + \text{CO} \]
- Therefore, **y = smelting**.

3. **Identify the Process for z (Impure Metal to Pure Metal)**:
- The final step is to purify the impure metal to obtain pure metal. This is typically achieved through **electrolysis**. In electrolysis, the impure metal is placed at the anode, and a pure metal sheet is used as the cathode. The metal ions from the impure metal dissolve and deposit on the cathode, resulting in pure metal.
- Therefore, **z = electrolysis**.

### Final Answer:
- x = roasting
- y = smelting
- z = electrolysis