Previous Year Questions with Solutions - Chemical Reactions and Equations
Understanding previous year questions related to chemical reactions and equations is crucial for mastering this topic. Here, we will discuss some key questions along with their solutions to help you prepare effectively.

Question 1:
What is the difference between a physical change and a chemical change? Provide examples of each.
- Physical change: A physical change does not alter the chemical composition of a substance. Examples include melting of ice, boiling of water, and cutting of paper.
- Chemical change: A chemical change results in the formation of new substances with different chemical properties. Examples include rusting of iron, burning of wood, and digestion of food.

Question 2:
Balance the following chemical equation: Fe + O2 → Fe2O3
- Solution:
2Fe + 3O2 → 2Fe2O3

Question 3:
What is the law of conservation of mass and how is it applied in balancing chemical equations?
- Law of conservation of mass: This law states that mass can neither be created nor destroyed in a chemical reaction.
- Application in balancing equations: When balancing chemical equations, the number of atoms of each element must be equal on both sides to satisfy this law.

Question 4:
Define endothermic and exothermic reactions. Provide examples of each.
- Endothermic reaction: An endothermic reaction absorbs heat from its surroundings, resulting in a decrease in temperature. Example: photosynthesis.
- Exothermic reaction: An exothermic reaction releases heat into its surroundings, resulting in an increase in temperature. Example: combustion.
By revisiting these previous year questions with solutions, you can strengthen your understanding of chemical reactions and equations. Practice more such questions to enhance your proficiency in this topic.