Which of the following reactions is an endothermic reaction?

Options

A. Burning of coal.
B. Decomposition of vegetable matter into compost.
C. Process of respiration.
D. Decomposition of calcium carbonate to form quick lime and carbon dioxide.

Explanation

To determine which of the following reactions is an endothermic reaction, we first need to understand what endothermic reactions are.

### Step-by-Step Solution:

1. **Define Endothermic Reactions**:
- Endothermic reactions are chemical reactions that absorb heat from their surroundings. This means that energy is required for the reaction to occur.

2. **Analyze the Given Reactions**:
- We will evaluate each reaction to see if it absorbs heat or releases heat.

3. **Evaluate Each Reaction**:
- **Burning of Coal**:
- This is a combustion reaction where coal (carbon) reacts with oxygen to produce carbon dioxide (CO2) and releases heat.
- **Conclusion**: This is an exothermic reaction.

- **Decomposition of Vegetable Matter into Compost**:
- This process involves microbial activity that breaks down organic matter and releases energy in the form of heat.
- **Conclusion**: This is also an exothermic reaction.

- **Process of Respiration**:
- In respiration, glucose reacts with oxygen to produce carbon dioxide and water, releasing energy.
- **Conclusion**: This is an exothermic reaction.

- **Decomposition of Calcium Carbonate (CaCO3)**:
- When calcium carbonate decomposes into calcium oxide (CaO) and carbon dioxide (CO2), it requires heat to break the bonds in the reactants.
- **Conclusion**: This is an endothermic reaction because it absorbs heat to proceed.

4. **Identify the Endothermic Reaction**:
- Based on the analysis, the decomposition of calcium carbonate (CaCO3) to form quicklime (CaO) and carbon dioxide (CO2) is the endothermic reaction.

### Final Answer:
The endothermic reaction among the options provided is the **decomposition of CaCO3 to form quicklime (CaO) and carbon dioxide (CO2)**.

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