Which of the following processes involves smelting?

Options

A. `ZnCO_3 overset("Heat")(rarr)ZnO + CO_2`
B. `Fe_2O_(3) + 3C overset("Heat")(rarr) 2Fe+3CO`
C. `2PbS + 3O_2 overset("Heat")(rarr) 2PbO + 2SO_2`
D. `Al_2O_(3.)2H_2O overset("Heat")(rarr)Al_2O_3+2H_2O`

Answer

To determine which process involves smelting, we need to understand what smelting is. Smelting is a metallurgical process that involves heating and melting an ore to extract a metal. This process typically involves the reduction of metal oxides using carbon or other reducing agents.

### Step-by-Step Solution:

1. **Understand Smelting**: Smelting is a process where an ore (usually an oxide) is heated in the presence of a reducing agent (often carbon) to extract the metal in its elemental form.

2. **Identify the Options**: We need to analyze the given options to see which one involves the reduction of a metal oxide.

3. **Analyze Each Option**:
- **Option 1**: Heating zinc carbonate to produce zinc oxide. This is not smelting because it does not involve the reduction of an oxide to obtain elemental zinc.
- **Option 2**: Reducing iron oxide (Fe2O3) to iron (Fe) by heating with carbon. This is a classic example of smelting, where the iron oxide is reduced to its elemental form.
- **Option 3**: Adding oxygen to a sulfide to produce sulfur dioxide. This is a combustion reaction, not smelting.
- **Option 4**: Heating a hydrated oxide to remove water. This is a dehydration process, not smelting.

4. **Conclusion**: The only process that involves smelting is **Option 2**, where iron oxide is reduced to iron.

### Final Answer:
The process that involves smelting is **Option 2: Reducing iron oxide to iron**.