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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 important questions on chemical reactions, balancing equations, oxidation, reduction, and reaction types with detailed step-by-step solutions for CBSE, State Board, Olympiad, and scholarship exam preparation.
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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 countless changes occurring around us every day. From digestion of food to rusting of iron, all these processes involve chemical changes. This chapter helps students understand how chemical reactions occur, how equations represent them, and the importance of balancing chemical equations.
What You Will Learn
✔ Chemical reactions and their characteristics
✔ Balanced chemical equations
✔ Combination reactions
✔ Decomposition reactions
✔ Oxidation and reduction
✔ Displacement reactions
✔ Everyday applications of chemical reactions
Why This Topic Is Important
Chemical reactions form the foundation of Chemistry. Understanding this chapter helps students learn advanced topics such as acids, bases, metals, electrochemistry, and organic chemistry. Questions from this chapter frequently appear in school exams, board exams, Olympiads, and competitive tests.
1. MCQ Questions with Detailed Solutions
Q1. Which of the following indicates that a chemical reaction has occurred?
A) Change in shape only
B) Change in size only
C) Formation of a gas
D) Change in position
Answer:
C) Formation of a gas
Concept Behind This Question
Evolution of gas is one of the common indicators of a chemical reaction.
Step-by-Step Solution
When a chemical reaction occurs, one or more observable changes may take place:
• Gas may be produced
• Colour may change
• Temperature may change
• A precipitate may form
Formation of gas clearly indicates a chemical reaction.
Therefore, the correct answer is C.
Exam Tip
Remember the common indicators of chemical reactions.
Q2. What is the balanced form of the equation?
$$\text{H}_2 + \text{O}_2 \rightarrow \text{H}_2\text{O}$$
A) $$2H_2 + O_2 \rightarrow 2H_2O$$
B) $$H_2 + O_2 \rightarrow H_2O$$
C) $$H_2 + 2O_2 \rightarrow H_2O$$
D) $$2H_2 + 2O_2 \rightarrow H_2O$$
Answer
$$2H_2 + O_2 \rightarrow 2H_2O$$
Useful Formula for this Question
Law of Conservation of Mass
Number of atoms on both sides must be equal.
Step-by-Step Solution
Reactants:
Hydrogen = 2 atoms
Oxygen = 2 atoms
Products:
Hydrogen = 2 atoms
Oxygen = 1 atom
Equation is not balanced.
Balanced equation:
$$2H_2 + O_2 \rightarrow 2H_2O$$
Now atoms are equal on both sides.
Exam Tip
Always count atoms of every element separately.
Q3. Which type of reaction is represented by:
$$CaO + H_2O \rightarrow Ca(OH)_2$$
A) Decomposition Reaction
B) Combination Reaction
C) Displacement Reaction
D) Double Displacement Reaction
Answer
B) Combination Reaction
Concept Behind This Question
Two substances combine to form a single product.
Step-by-Step Solution
Reactants:
$$CaO$$ and $$H_2O$$
Product:
$$Ca(OH)_2$$
Since two reactants combine to form one product, it is a Combination Reaction.
Exam Tip
One product usually indicates a combination reaction.
Q4. Which substance undergoes oxidation in the following reaction?
$$CuO + H_2 \rightarrow Cu + H_2O$$
A) Copper Oxide
B) Copper
C) Hydrogen
D) Water
Answer
C) Hydrogen
Concept Behind This Question
Oxidation means addition of oxygen or removal of hydrogen.
Step-by-Step Solution
Hydrogen gains oxygen to form water.
$$H_2 \rightarrow H_2O$$
Therefore hydrogen is oxidized.
Exam Tip
Remember:
Addition of oxygen = Oxidation
Removal of oxygen = Reduction
Q5. Rusting of iron is an example of:
A) Oxidation
B) Reduction
C) Neutralization
D) Evaporation
Answer
A) Oxidation
Useful Concept
Rusting occurs when iron reacts with oxygen and moisture.
Step-by-Step Solution
Iron combines with oxygen:
$$Fe + O_2 \rightarrow Fe_2O_3$$
This addition of oxygen is oxidation.
Therefore rusting is an oxidation reaction.
Exam Tip
Rusting is one of the most common real-life examples of oxidation.
Important Formulas & Concepts
1. Law of Conservation of Mass
Mass of reactants = Mass of products
2. Combination Reaction
Two or more substances combine to form one product.
3. Decomposition Reaction
One compound breaks into two or more simpler substances.
4. Oxidation
Addition of oxygen or removal of hydrogen.
5. Reduction
Removal of oxygen or addition of hydrogen.
Related Practice Questions
- What is a balanced chemical equation?
- Give one example of a decomposition reaction.
- Why is balancing a chemical equation important?
- Define oxidation with an example.
- What are the signs of a chemical reaction?
Mini Quiz Challenge
Fill in the blanks
- Rusting is a type of __________ reaction.
- In a balanced equation, the number of atoms on both sides remains __________.
- Addition of oxygen is called __________.
Answers
- Oxidation
- Equal
- Oxidation
Exam Tips
✔ Learn all reaction types with examples.
✔ Practice balancing equations daily.
✔ Remember oxidation and reduction definitions.
✔ Focus on NCERT activities and examples.
✔ Learn real-life applications of chemical reactions.
Quick Revision Notes
✔ Chemical reactions produce new substances.
✔ Gas evolution indicates a reaction.
✔ Balanced equations obey the law of conservation of mass.
✔ Combination reactions form a single product.
✔ Oxidation means gain of oxygen.
✔ Reduction means loss of oxygen.
✔ Rusting is an oxidation reaction.
Common Mistakes Students Make
❌ Forgetting to balance equations.
❌ Confusing oxidation with reduction.
❌ Ignoring coefficients while counting atoms.
❌ Memorizing reactions without understanding concepts.
❌ Mixing combination and decomposition reactions.
Key Takeaways
✔ Chemical reactions cause chemical changes.
✔ Balanced equations have equal atoms on both sides.
✔ Combination reactions produce a single product.
✔ Oxidation involves gain of oxygen.
✔ Reduction involves loss of oxygen.
✔ Rusting is an important oxidation process.
FAQs
1. Why do we balance chemical equations?
To satisfy the law of conservation of mass.
2. What is oxidation?
Addition of oxygen or removal of hydrogen.
3. What is reduction?
Removal of oxygen or addition of hydrogen.
4. What is a combination reaction?
A reaction in which two or more substances form a single product.
5. Why is rusting harmful?
It weakens iron objects and causes damage.
Conclusion
Chemical Reactions and Equations is one of the most important chapters of Class 10 Science. Understanding reaction types, balancing equations, oxidation, and reduction helps students build a strong foundation in Chemistry. Regular practice of MCQs improves conceptual understanding and boosts exam performance.
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