Chemical Reactions and Equations (Most Important and Repealed Question in Board PYQ (just For Practice))

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Chemical Reactions and Equations - Class 10

🔥 Most Important Questions

1. Define a chemical reaction. What are the characteristics of a chemical reaction?
2. Write the balanced chemical equations for the following reactions:
   • Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen
   • Calcium carbonate → Calcium oxide + Carbon dioxide
3. What is a balanced chemical equation? Why should chemical equations be balanced?
4. Explain the different types of chemical reactions with one example each:
   • Combination
   • Decomposition
   • Displacement
   • Double displacement
   • Redox
5. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
6. What is rancidity? How can it be prevented?
7. What happens when:
   • Zinc reacts with dilute sulphuric acid?
   • Lead nitrate is heated?
   • A piece of iron is placed in copper sulphate solution?

📘 Most Repeated Previous Year Questions (PYQs)

1. Write a balanced chemical equation for the reaction between sodium and water.
2. What is the difference between a physical change and a chemical change? Give one example of each.
3. What is oxidation and reduction? Explain with examples.
4. Give an example of a redox reaction and identify the oxidised and reduced substances.
5. A student adds dilute HCl to Zn granules and notices bubbles. Why? What gas is evolved?
6. Why is photosynthesis considered an endothermic reaction?
7. Write the balanced chemical equation for the thermal decomposition of lead nitrate. State the type of reaction also.
8. What is a precipitation reaction? Explain with an example.

Tip: Practice these questions well and focus on the types of reactions and equation balancing—they are commonly tested in board exams.