Which of the following processes involve the roasting process ?

Options

A. `ZnCO_(3) to ZnO + CO_(2)`
B. `Fe_(2)O_(3) + 3C to 2Fe + 3CO`
C. `2PbS + 3O_(2) to 2PbO + 2SO_(2)`
D. `Al_(2)O_(3).2H_(2)O to Al_(2)O_(3) + 2H_(2) O`

Explanation

To determine which of the given processes involves roasting, we need to understand what roasting is and identify the correct reaction from the options provided.

### Step-by-Step Solution:

1. **Understand the Definition of Roasting**:
- Roasting is a metallurgical process where a sulfide ore is heated in the presence of excess air (or oxygen) to convert it into its oxide. This process typically occurs below the melting point of the ore.

2. **Identify the Key Components of Roasting**:
- The process requires:
- A sulfide ore (the starting material).
- Excess air or oxygen (to facilitate the conversion).
- The formation of an oxide (the end product).

3. **Analyze the Given Options**:
- Look at each option provided in the question and check for the presence of a sulfide ore, excess air, and the conversion to an oxide.

4. **Evaluate Each Option**:
- For each option, determine if it meets the criteria for roasting:
- **Option A**: Check if it involves a sulfide ore and excess air.
- **Option B**: Check the same.
- **Option C**: Check if it involves a sulfide ore and excess air. For example, if it states that lead sulfide (PbS) is heated with air to form lead oxide (PbO), this would be roasting.
- **Option D**: Check the same.

5. **Select the Correct Option**:
- After evaluating all options, identify which option clearly describes the roasting process. In this case, if Option C describes the conversion of lead sulfide (PbS) to lead oxide (PbO) with excess air, then this is the roasting process.

6. **Final Answer**:
- The correct answer is **Option C**, as it involves the roasting process by converting a sulfide ore (lead sulfide) into its oxide (lead oxide) in the presence of excess air.