Roasting results in the production of metal in the case of:

Options

A. Cinnabar
B. Iron pyrites
C. Bauxite
D. Galena

Answer

To solve the question "Roasting results in the production of metal in the case of:", we need to analyze the given options and understand the process of roasting.

### Step-by-Step Solution:

1. **Understand the Process of Roasting**:
- Roasting is a metallurgical process involving the heating of ores in the presence of excess air (oxygen). This process typically converts sulfide ores into oxides.

2. **Identify the Given Options**:
- The options provided are:
1. Cinnabar (HgS)
2. Iron pyrites (FeS2)
3. Bauxite (Al2O3·2H2O)
4. Galena (PbS)

3. **Analyze Each Option**:
- **Option 1: Cinnabar (HgS)**:
- When cinnabar is roasted, it reacts with oxygen to form mercury(II) oxide (HgO) and sulfur dioxide (SO2):
\[ 2 \text{HgS} + 3 \text{O}_2 \rightarrow 2 \text{HgO} + 2 \text{SO}_2 \]
- HgO is unstable and decomposes to produce metallic mercury (Hg):
\[ 2 \text{HgO} \rightarrow 2 \text{Hg} + \text{O}_2 \]
- Thus, roasting cinnabar results in the production of metallic mercury.

- **Option 2: Iron Pyrites (FeS2)**:
- Roasting iron pyrites produces iron oxides (FeO and Fe2O3) and sulfur dioxide:
\[ 4 \text{FeS}_2 + 11 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 + 8 \text{SO}_2 \]
- Here, we do not obtain metallic iron directly.

- **Option 3: Bauxite (Al2O3·2H2O)**:
- Roasting bauxite leads to the formation of aluminum oxide (Al2O3) and water vapor:
\[ \text{Al}_2\text{O}_3 \cdot 2 \text{H}_2\text{O} \rightarrow \text{Al}_2\text{O}_3 + 2 \text{H}_2\text{O} \]
- No metal is produced directly from roasting.

- **Option 4: Galena (PbS)**:
- Roasting galena results in lead(II) oxide (PbO) and sulfur dioxide:
\[ 2 \text{PbS} + 3 \text{O}_2 \rightarrow 2 \text{PbO} + 2 \text{SO}_2 \]
- Again, no metallic lead is produced directly from roasting.

4. **Conclusion**:
- Among the options analyzed, only roasting of **Cinnabar (HgS)** results in the production of a metal (mercury). Therefore, the correct answer is **Option 1: Cinnabar**.

### Final Answer:
Roasting results in the production of metal in the case of **Cinnabar (HgS)**.