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Practice Class 10 Science Chapter 1 Chemical Reactions and Equations MCQ Questions with Answers based on the latest NCERT syllabus. Solve challenging MCQs on reaction types, energy changes, oxidation, reduction, corrosion, and everyday chemical reactions with detailed step-by-step solutions for CBSE, State Board, Olympiad, and scholarship exams.
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Chapter Information
Subject: Science
Class: 10
Chapter: Chemical Reactions and Equations
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Moderate to Difficult
Based On: NCERT Latest Syllabus (2026)
Introduction
Chemical reactions are responsible for numerous changes in nature and daily life. They help produce useful substances, generate energy, and support biological processes. Understanding the different types of reactions and their applications is essential for mastering chemistry.
What You Will Learn
✔ Identification of reaction types
✔ Energy changes during reactions
✔ Oxidation and reduction concepts
✔ Corrosion and its effects
✔ Everyday applications of chemistry
✔ Chemical equation analysis
✔ Higher-order thinking skills
Why This Topic Is Important?
The concepts covered in this chapter form the basis for future chemistry studies. Questions based on reaction classification, oxidation, corrosion, and balancing equations frequently appear in board examinations and competitive tests.
1. MCQ Questions with Detailed Solutions
Q1. Which of the following reactions is an example of a decomposition reaction caused by electricity?
A) $$2H_2 + O_2 \rightarrow 2H_2O$$
B) $$2H_2O \rightarrow 2H_2 + O_2$$
C) $$Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$$
D) $$CaO + H_2O \rightarrow Ca(OH)_2$$
Answer
B) $$2H_2O \rightarrow 2H_2 + O_2$$
Concept Behind This Question
Electricity can break compounds into simpler substances.
Step-by-Step Solution
Water decomposes into hydrogen and oxygen when electric current is passed through it.
$$2H_2O \rightarrow 2H_2 + O_2$$
This is an electrolytic decomposition reaction.
Exam Tip
Remember that electrolysis uses electricity to decompose compounds.
Q2. Which reaction represents reduction?
A) $$2Mg + O_2 \rightarrow 2MgO$$
B) $$2Cu + O_2 \rightarrow 2CuO$$
C) $$CuO + H_2 \rightarrow Cu + H_2O$$
D) $$C + O_2 \rightarrow CO_2$$
Answer
C) $$CuO + H_2 \rightarrow Cu + H_2O$$
Useful Concept for this Question
Reduction means removal of oxygen.
Step-by-Step Solution
Copper oxide loses oxygen and becomes copper.
$$CuO \rightarrow Cu$$
Since oxygen is removed, reduction occurs.
Therefore, option C is correct.
Exam Tip
Loss of oxygen = Reduction.
Q3. Which of the following reactions releases heat and light?
A) Rusting of iron
B) Burning of LPG
C) Melting of ice
D) Dissolving sugar in water
Answer
B) Burning of LPG
Concept Behind This Question
Combustion reactions release heat and light.
Step-by-Step Solution
LPG reacts with oxygen and produces energy.
This energy appears as heat and light.
Therefore, burning LPG is an exothermic combustion reaction.
Exam Tip
Most fuel-burning reactions are exothermic.
Q4. Which of the following is used to prevent food rancidity?
A) Storing food in open containers
B) Exposure to sunlight
C) Nitrogen-filled packaging
D) Keeping food moist
Answer
C) Nitrogen-filled packaging
Concept Behind This Question
Nitrogen prevents oxidation of oils and fats.
Step-by-Step Solution
Rancidity occurs due to oxidation.
Nitrogen is less reactive and prevents contact with oxygen.
Therefore, nitrogen-filled packets help prevent rancidity.
Exam Tip
Chips packets are often filled with nitrogen gas.
Q5. Identify the type of reaction:
$$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$
A) Combination Reaction
B) Decomposition Reaction
C) Displacement Reaction
D) Neutralization Reaction
Answer
C) Displacement Reaction
Concept Behind This Question
A more reactive metal replaces a less reactive metal.
Step-by-Step Solution
Iron is more reactive than copper.
Therefore, iron displaces copper from copper sulphate solution.
$$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$
Hence, it is a displacement reaction.
Exam Tip
Check the metal reactivity series to identify displacement reactions.
Important Formulas & Concepts
1. Electrolytic Decomposition
Decomposition caused by electric current.
Example:
$$2H_2O \rightarrow 2H_2 + O_2$$
2. Reduction
Removal of oxygen or addition of hydrogen.
3. Combustion Reaction
A reaction that releases heat and light by burning in oxygen.
4. Rancidity
Oxidation of fats and oils causing spoilage.
5. Displacement Reaction
A more reactive element replaces a less reactive element.
Related Practice Questions
- What is electrolysis?
- Define reduction with an example.
- Why are chips packets filled with nitrogen?
- What is a displacement reaction?
- Why is burning LPG an exothermic reaction?
Mini Quiz Challenge
Fill in the blanks
- Electrolysis uses __________ current.
- Removal of oxygen is called __________.
- Nitrogen helps prevent __________.
Answers
- Electric
- Reduction
- Rancidity
Exam Tips
✔ Revise oxidation and reduction together.
✔ Learn examples of decomposition reactions.
✔ Understand real-life applications of nitrogen gas.
✔ Practice reaction identification questions.
✔ Remember important NCERT reaction equations.
Quick Revision Notes
✔ Water decomposes into hydrogen and oxygen during electrolysis.
✔ Reduction means removal of oxygen.
✔ Burning LPG releases heat and light.
✔ Nitrogen-filled packets prevent rancidity.
✔ Iron displaces copper from copper sulphate solution.
✔ Combustion reactions are exothermic.
✔ Displacement reactions depend on reactivity.
Common Mistakes Students Make
❌ Confusing oxidation with reduction.
❌ Forgetting the purpose of nitrogen in food packaging.
❌ Mixing decomposition and displacement reactions.
❌ Ignoring the metal reactivity series.
❌ Memorizing equations without understanding concepts.
Key Takeaways
✔ Electricity can decompose compounds.
✔ Reduction involves loss of oxygen.
✔ Fuel combustion releases heat and light.
✔ Nitrogen prevents oxidation of food.
✔ Displacement reactions occur due to differences in reactivity.
✔ Understanding reaction types improves exam performance.
FAQs
1. What is electrolysis?
The decomposition of a compound using electric current.
2. What is reduction?
Removal of oxygen or addition of hydrogen.
3. Why are snack packets filled with nitrogen?
To prevent rancidity caused by oxidation.
4. What is a displacement reaction?
A reaction where a more reactive element replaces a less reactive element.
5. Why is LPG considered a useful fuel?
Because it releases a large amount of heat energy when burned.
Conclusion
Chemical reactions are essential in both nature and technology. Understanding electrolysis, reduction, combustion, rancidity, and displacement reactions helps students strengthen their chemistry concepts and perform confidently in examinations.
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