Which of the following reactions are exothermic in nature?

Options

A. Combustion of Carbon
B. Bond breaking
C. Bond formation
D. Both (a) and (c)

Answer

To determine which of the following reactions are exothermic in nature, we need to understand the definition of exothermic reactions and analyze the reactions provided.

### Step-by-Step Solution:

1. **Understand Exothermic Reactions**:
- An exothermic reaction is one that releases heat to the surroundings. This means that the products of the reaction have lower energy than the reactants.

2. **Identify Combustion Reactions**:
- Combustion reactions are typically exothermic. For example, the combustion of carbon in the presence of oxygen produces carbon dioxide (CO2) and releases heat.

3. **Analyze Bond Formation and Breaking**:
- Bond formation releases energy, making those reactions exothermic. Conversely, breaking bonds requires energy input, making those reactions endothermic.

4. **Evaluate Given Reactions**:
- If the question provides specific reactions, evaluate each one based on whether they release heat (exothermic) or absorb heat (endothermic).

5. **Conclusion**:
- After analyzing the reactions, list those that are exothermic based on the criteria above.

### Example Reactions:
- **Combustion of Carbon**: Exothermic (heat is released)
- **Dissolving Ammonium Nitrate in Water**: Endothermic (heat is absorbed)
- **Formation of Water from Hydrogen and Oxygen**: Exothermic (heat is released)

### Final Answer:
- The reactions that are exothermic in nature include combustion reactions and reactions that involve bond formation.