Heat is evolved during

Options

A. endothermic reaction
B. displacement reaction
C. combustion reaction
D. combination reaction

Explanation

To determine which type of reaction evolves heat, we can analyze the options provided:

1. **Endothermic Reaction**:
- In an endothermic reaction, heat is absorbed from the surroundings. Therefore, heat is not evolved in this type of reaction.
- **Conclusion**: This option does not evolve heat.

2. **Displacement Reaction**:
- A displacement reaction involves one element replacing another in a compound (e.g., A + BC → AC + B).
- In some cases, heat may be released or absorbed depending on the specific reactants and products involved. Thus, heat can either evolve or be absorbed.
- **Conclusion**: This option can evolve heat, but it is not guaranteed.

3. **Combustion Reaction**:
- A combustion reaction involves the oxidation of a hydrocarbon in the presence of oxygen, producing carbon dioxide, water, and heat (e.g., CH₄ + O₂ → CO₂ + H₂O + heat).
- This type of reaction is always exothermic, meaning it consistently releases heat.
- **Conclusion**: This option definitely evolves heat.

4. **Combination Reaction**:
- A combination reaction involves two or more substances combining to form a single product (e.g., A + B → AB).
- This type of reaction can be either exothermic or endothermic, depending on the specific substances involved.
- **Conclusion**: This option can evolve heat, but it is not certain.

**Final Answer**: The most appropriate option where heat is evolved is **C) Combustion Reaction**.