Which of the following reaction occur during calcination ?

Options

A. `CaCO_(3) to CaO+CO_(2)`
B. `2FeS_(2)+(11)/(2)O_(2) to Fe_(2)O_(3)+4SO_(2)`
C. `Al_(2)O_(3).xH_(2)O to Al_(2)O_(3)+xH_(2)O`
D. `ZnS+(3)/(2)O_(2) to ZnO+SO_(2)`

Explanation

### Step-by-Step Solution:

1. **Understanding Calcination**:
- Calcination is a thermal treatment process that involves heating ores in the absence of air or in a limited supply of air. The primary aim is to drive off volatile substances, such as water or carbon dioxide, and to convert the ore into a more useful form.

2. **Identifying Types of Ores**:
- The ores that typically undergo calcination include:
- Carbonates (e.g., CaCO₃)
- Hydroxides (e.g., Al(OH)₃)
- Oxides (e.g., ZnO)
- Sulfides (e.g., FeS) do not undergo calcination but rather undergo roasting.

3. **Analyzing the Given Options**:
- The question provides multiple reactions, and we need to identify which of these reactions represent calcination.
- Look for reactions involving the decomposition of carbonates, hydroxides, or oxides.

4. **Examples of Calcination Reactions**:
- For carbonates:
\[ \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2 \uparrow \]
- For hydroxides:
\[ \text{2Al(OH)}_3 \rightarrow \text{Al}_2\text{O}_3 + 3\text{H}_2\text{O} \uparrow \]
- Oxides do not decompose further in calcination but are often produced from the calcination of carbonates or hydroxides.

5. **Conclusion**:
- Based on the analysis, the reactions that occur during calcination are those involving carbonates and hydroxides. Therefore, the correct options for the reactions that occur during calcination are the ones that involve carbonates and hydroxides.

### Final Answer:
- The reactions that occur during calcination are those involving carbonates and hydroxides.