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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 higher-order MCQs on redox reactions, reaction observations, corrosion, balancing equations, and chemical changes with detailed 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 involve the conversion of reactants into products through the rearrangement of atoms. Understanding how to identify reaction types, recognize chemical changes, and interpret equations helps students develop a deeper understanding of chemistry and its applications.
What You Will Learn
✔ Redox reactions
✔ Observation-based chemistry
✔ Corrosion and prevention
✔ Balancing chemical equations
✔ Application-based questions
✔ Chemical versus physical changes
✔ NCERT concept mastery
Why This Topic Is Important?
Chemical Reactions and Equations is the foundation of chemistry. A strong understanding of reaction types and chemical processes helps students solve board-level, Olympiad, and scholarship examination questions accurately.
1. MCQ Questions with Detailed Solutions
Q1. Which of the following reactions is both oxidation and reduction occurring simultaneously?
A) $$CaO + H_2O \rightarrow Ca(OH)_2$$
B) $$CuO + H_2 \rightarrow Cu + H_2O$$
C) $$CaCO_3 \rightarrow CaO + CO_2$$
D) $$2Mg + O_2 \rightarrow 2MgO$$
Answer
B) $$CuO + H_2 \rightarrow Cu + H_2O$$
Concept Behind This Question
A redox reaction involves oxidation and reduction occurring together.
Step-by-Step Solution
In the reaction:
$$CuO + H_2 \rightarrow Cu + H_2O$$
Hydrogen gains oxygen and is oxidized.
Copper oxide loses oxygen and is reduced.
Therefore, both processes occur simultaneously.
Hence, it is a redox reaction.
Exam Tip
If one substance is oxidized and another is reduced in the same reaction, it is a redox reaction.
Q2. A student observes bubbles forming when dilute hydrochloric acid reacts with zinc granules. What do these bubbles indicate?
A) Formation of a precipitate
B) Evolution of a gas
C) Colour change
D) Physical change only
Answer
B) Evolution of a gas
Concept Behind This Question
Gas evolution is a common indicator of a chemical reaction.
Step-by-Step Solution
Reaction:
$$Zn + 2HCl \rightarrow ZnCl_2 + H_2$$
Hydrogen gas is produced.
The bubbles observed are due to hydrogen gas.
Therefore, the correct answer is evolution of a gas.
Exam Tip
Bubbles during a chemical reaction often indicate gas formation.
Q3. Which of the following metals is least likely to undergo corrosion under normal conditions?
A) Iron
B) Copper
C) Silver
D) Gold
Answer
D) Gold
Concept Behind This Question
Less reactive metals resist corrosion better.
Step-by-Step Solution
Gold is a very unreactive metal.
It does not react easily with air or moisture.
Therefore, it is highly resistant to corrosion.
Exam Tip
Noble metals such as gold show excellent corrosion resistance.
Q4. What is the coefficient of oxygen in the balanced equation?
$$2KClO_3 \rightarrow 2KCl + ?O_2$$
A) 2
B) 3
C) 4
D) 5
Answer
B) 3
Useful Formula for this Question
The number of atoms must remain equal on both sides.
Step-by-Step Solution
Left side:
$$2KClO_3$$ contains 6 oxygen atoms.
To balance oxygen:
$$2KClO_3 \rightarrow 2KCl + 3O_2$$
Right side:
$$3 \times 2 = 6$$ oxygen atoms.
Therefore, the coefficient is:
$$3$$
Exam Tip
Count oxygen atoms carefully while balancing decomposition equations.
Q5. Which of the following represents a chemical change?
A) Crushing chalk
B) Cutting paper
C) Digestion of food
D) Breaking glass
Answer
C) Digestion of food
Concept Behind This Question
Chemical changes produce new substances.
Step-by-Step Solution
During digestion, food is chemically broken down into simpler substances.
New substances are formed.
Therefore, digestion is a chemical change.
The other options are physical changes.
Exam Tip
If the composition changes and new substances are formed, it is a chemical change.
Important Formulas & Concepts
1. Redox Reaction
Oxidation and reduction occur simultaneously.
Example:
$$CuO + H_2 \rightarrow Cu + H_2O$$
2. Oxidation
Addition of oxygen or removal of hydrogen.
3. Reduction
Removal of oxygen or addition of hydrogen.
4. Corrosion Resistance
Less reactive metals generally resist corrosion better.
5. Chemical Change
A process that produces one or more new substances.
Related Practice Questions
- What is a redox reaction?
- Why is gold resistant to corrosion?
- What are the common indicators of a chemical reaction?
- Define oxidation and reduction.
- Why is digestion considered a chemical change?
Mini Quiz Challenge
Fill in the blanks
- A redox reaction involves __________ and reduction.
- Hydrogen gas is produced when zinc reacts with __________ acid.
- Gold is a highly __________ metal.
Answers
- Oxidation
- Hydrochloric
- Unreactive
Exam Tips
✔ Learn the difference between physical and chemical changes.
✔ Practice balancing decomposition equations.
✔ Revise oxidation and reduction definitions.
✔ Focus on real-life examples from NCERT.
✔ Understand observation-based chemistry questions.
Quick Revision Notes
✔ Redox reactions involve oxidation and reduction together.
✔ Gas evolution indicates a chemical reaction.
✔ Gold is highly resistant to corrosion.
✔ Potassium chlorate decomposes to potassium chloride and oxygen.
✔ Digestion is a chemical change.
✔ New substances are formed during chemical reactions.
✔ Balancing equations follows the law of conservation of mass.
Common Mistakes Students Make
❌ Confusing physical changes with chemical changes.
❌ Forgetting that redox reactions involve both oxidation and reduction.
❌ Incorrectly balancing oxygen in decomposition reactions.
❌ Assuming all metals corrode at the same rate.
❌ Ignoring reaction observations.
Key Takeaways
✔ Redox reactions involve simultaneous oxidation and reduction.
✔ Gas formation is a common sign of chemical reactions.
✔ Gold is highly resistant to corrosion.
✔ Balanced equations have equal atoms on both sides.
✔ Digestion is an important example of a chemical change.
✔ Understanding reaction observations improves problem-solving skills.
FAQs
1. What is a redox reaction?
A reaction in which oxidation and reduction occur together.
2. Why does zinc react with hydrochloric acid?
Because zinc is more reactive than hydrogen and displaces it from the acid.
3. Why is gold resistant to corrosion?
Because it is a very unreactive metal.
4. What is a chemical change?
A change that produces new substances.
5. Why are chemical equations balanced?
To satisfy the law of conservation of mass.
Conclusion
Understanding redox reactions, chemical changes, corrosion resistance, and balancing equations helps students develop strong chemistry fundamentals. Regular practice of concept-based MCQs improves accuracy and confidence in examinations.
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