Endothermic Reaction MCQs Quiz | Class 10
Class 10 Science (Code 086), Unit I: Chemical Substances – Nature and Behaviour. This quiz covers the topic of Endothermic Reactions, focusing on heat absorption, identification of specific reactions, and examples such as thermal decomposition. Test your knowledge with these 10 MCQs, check your score, and download the detailed answer PDF for exam preparation.
Understanding Endothermic Reactions
An endothermic reaction is a chemical process that absorbs energy from its surroundings, usually in the form of heat. Because energy is taken in, the temperature of the immediate surroundings typically decreases. In these reactions, the energy required to break the bonds of the reactants is greater than the energy released when new bonds form in the products.
Key Characteristics
- Heat Absorption: The system gains heat from the surroundings.
- Temperature Drop: The surroundings feel colder.
- Enthalpy Change: The change in enthalpy (Delta H) is positive (+).
Common Examples
Many decomposition reactions are endothermic because they require energy input (heat, light, or electricity) to break down compounds:
- Photosynthesis: Green plants absorb solar energy to convert carbon dioxide and water into glucose.
- Thermal Decomposition of Calcium Carbonate: Limestone (CaCO3) absorbs heat to decompose into quicklime (CaO) and carbon dioxide (CO2).
- Electrolysis of Water: Electrical energy is absorbed to split water into hydrogen and oxygen.
- Evaporation: Liquid water absorbing heat to turn into vapor (a physical change, but endothermic process).
Comparison: Endothermic vs Exothermic
| Feature | Endothermic | Exothermic |
|---|---|---|
| Energy Flow | Absorbed from surroundings | Released to surroundings |
| Temperature | Surroundings cool down | Surroundings heat up |
| Enthalpy (Delta H) | Positive | Negative |
Extra Practice Questions
- Why is respiration considered exothermic while photosynthesis is endothermic?
- Write the chemical equation for the thermal decomposition of Lead Nitrate.
- What happens when you mix Barium Hydroxide and Ammonium Chloride in a beaker?
- Define photolytic decomposition with an example.
- Is the melting of ice an endothermic or exothermic process?
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