Preparing for the CBSE board exam becomes much easier when concepts are practised through questions. Chemical Reactions and Equations is the first chapter of Class 10 Science and it builds the foundation of chemistry for the complete syllabus. From balancing equations to understanding oxidation and reduction, every topic in this chapter is important for exams as well as higher classes.
These Chemical Reactions and Equations Class 10 MCQs are designed to help students practise important objective questions based on the latest CBSE exam pattern. Regular MCQs practice improves conceptual understanding, accuracy, speed, and confidence during exams.
On this page, students can practise important Chemical Reactions and Equations Class 10 MCQs with answers and explanations designed according to the latest CBSE Board exam pattern. These objective questions help in quick revision, concept clarity, and better preparation for board exams.
Students preparing for board exams can also explore all chapter-wise questions from the Class 10 Science MCQs collection for complete subject-wise practice and revision.
Chemical Reactions and Equations Class 10 MCQs with Answers
Practising Chemical Reactions and Equations Class 10 MCQs is one of the most effective ways to prepare for the CBSE board exam. These objective questions help students understand important concepts like balancing equations, identifying reaction types, oxidation and reduction, corrosion, and rancidity in a more practical way. Solving MCQs regularly also improves speed, accuracy, and confidence while attempting exam-based chemistry questions.
Q. A chemical reaction in which two or more substances combine to form a single product is called:
A. Displacement reaction
B. Combination reaction
C. Decomposition reaction
D. Neutralisation reaction
Answer: B
Explanation:
A combination reaction takes place when multiple reactants join together to produce one product. These reactions usually release energy in the form of heat or light.
Q. A student heats ferrous sulphate crystals in a test tube. The crystals first lose water and then decompose. Which type of reaction is involved?
A. Combination reaction
B. Thermal decomposition reaction
C. Double displacement reaction
D. Neutralisation reaction
Answer: B
Explanation:
When heat causes a compound to break into simpler substances, the process is called thermal decomposition. Ferrous sulphate decomposes on strong heating.
Q. Which of the following substances acts as a reactant in the formation of magnesium oxide?
A. Carbon dioxide
B. Magnesium
C. Calcium carbonate
D. Sodium chloride
Answer: B
Explanation:
Magnesium reacts with oxygen present in air to produce magnesium oxide. The substances taking part in the reaction are known as reactants.
Q. In a balanced chemical equation, the total number of atoms remains:
A. Different on both sides
B. Equal on both sides
C. Zero on product side
D. Double on reactant side
Answer: B
Explanation:
According to the law of conservation of mass, atoms cannot be created or destroyed during a chemical reaction. Therefore, the number of atoms remains equal on both sides.
Q. What is observed when magnesium ribbon burns in air?
A. Green flame with black ash
B. Yellow flame with brown residue
C. Bright white flame with white powder
D. Blue flame with gas evolution
Answer: C
Explanation:
Magnesium burns with a dazzling white flame and forms magnesium oxide, which appears as a white powdery ash.
Q. Which gas is commonly released when zinc reacts with dilute hydrochloric acid?
A. Oxygen
B. Hydrogen
C. Nitrogen
D. Carbon dioxide
Answer: B
Explanation:
Zinc reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen gas. Hydrogen is colourless and burns with a popping sound.
Q. A reaction where one metal replaces another metal from its salt solution is known as:
A. Combination reaction
B. Redox reaction
C. Displacement reaction
D. Decomposition reaction
Answer: C
Explanation:
In a displacement reaction, a more reactive metal replaces a less reactive metal from its compound or solution.
Q. Which of the following is the correct chemical formula for aluminium oxide?
A. AlO
B. Al₂O₃
C. AlO₂
D. Al₃O₂
Answer: B
Explanation:
Aluminium combines with oxygen in the ratio required to balance their valencies, forming aluminium oxide with the formula Al₂O₃.
Q. What happens when carbon dioxide gas is passed through lime water?
A. Lime water becomes colourless
B. Blue precipitate forms
C. Lime water turns milky
D. Hydrogen gas evolves
Answer: C
Explanation:
Carbon dioxide reacts with calcium hydroxide in lime water to form calcium carbonate, which gives a milky appearance.
Q. Which process is considered a chemical change?
A. Breaking glass
B. Boiling water
C. Rusting of iron
D. Cutting paper
Answer: C
Explanation:
Rusting forms a new substance called hydrated iron oxide. Since a new substance is produced, it is a chemical change.
Q. The reaction between silver nitrate and sodium chloride produces a white precipitate of:
A. Silver oxide
B. Silver chloride
C. Sodium nitrate
D. Sodium oxide
Answer: B
Explanation:
When silver nitrate reacts with sodium chloride, insoluble silver chloride is formed as a white precipitate.
Q. Oxidation in a chemical reaction involves:
A. Gain of oxygen
B. Loss of oxygen
C. Gain of electrons
D. Removal of hydrogen only
Answer: A
Explanation:
Oxidation commonly refers to the addition of oxygen to a substance or removal of hydrogen from it.
Q. Which type of reaction occurs when electricity is used to split water into hydrogen and oxygen?
A. Combination reaction
B. Electrolytic decomposition reaction
C. Displacement reaction
D. Neutralisation reaction
Answer: B
Explanation:
Electric current causes water molecules to break into hydrogen and oxygen gases. This process is called electrolytic decomposition.
Q. A brown gas is released when lead nitrate is heated strongly. The gas is:
A. Hydrogen
B. Nitrogen dioxide
C. Sulphur dioxide
D. Oxygen
Answer: B
Explanation:
Lead nitrate decomposes on heating to produce lead oxide, oxygen, and nitrogen dioxide gas, which appears brown in colour.
Q. Which of the following reactions is an example of a combination reaction?
A. CaCO₃ → CaO + CO₂
B. Zn + CuSO₄ → ZnSO₄ + Cu
C. 2Mg + O₂ → 2MgO
D. AgNO₃ + NaCl → AgCl + NaNO₃
Answer: C
Explanation:
In this reaction, magnesium and oxygen combine to form a single product, magnesium oxide, making it a combination reaction.
Q. Food items containing oils and fats are flushed with nitrogen gas mainly to:
A. Increase flavour
B. Reduce weight
C. Prevent rancidity
D. Improve colour
Answer: C
Explanation:
Nitrogen prevents oxidation of fats and oils, reducing the chances of rancidity and increasing shelf life.
Q. Which observation indicates that a chemical reaction has taken place?
A. Change in shape only
B. Formation of gas
C. Increase in size
D. Breaking into pieces
Answer: B
Explanation:
Gas evolution is a common indicator of a chemical reaction because it suggests the formation of a new substance.
Q. The black coating formed on silver articles exposed to air is mainly due to:
A. Silver nitrate
B. Silver sulphide
C. Silver oxide
D. Silver chloride
Answer: B
Explanation:
Silver reacts slowly with sulphur compounds in air to form silver sulphide, which appears as a black layer.
Q. Which substance undergoes decomposition in the presence of sunlight during black-and-white photography?
A. Silver bromide
B. Sodium chloride
C. Copper sulphate
D. Calcium oxide
Answer: A
Explanation:
Silver bromide decomposes when exposed to light, producing silver metal. This reaction is used in traditional photography.
Q. The reaction between an acid and a base to form salt and water is called:
A. Decomposition reaction
B. Neutralisation reaction
C. Redox reaction
D. Displacement reaction
Answer: B
Explanation:
In a neutralisation reaction, acids react with bases to produce salt and water, usually releasing heat.
Q. Which of the following is a balanced chemical equation?
A. H₂ + O₂ → H₂O
B. 2H₂ + O₂ → 2H₂O
C. H₂ + O₂ → 2H₂O
D. H₂ + 2O₂ → H₂O
Answer: B
Explanation:
The equation is balanced because the number of hydrogen and oxygen atoms is equal on both sides of the reaction.
Q. What is the colour of copper sulphate solution before a displacement reaction with iron?
A. Green
B. Blue
C. Yellow
D. Colourless
Answer: B
Explanation:
Copper sulphate solution has a characteristic blue colour due to the presence of copper ions.
Q. Which reaction releases heat energy to the surroundings?
A. Endothermic reaction
B. Photolytic reaction
C. Exothermic reaction
D. Electrolytic reaction
Answer: C
Explanation:
Exothermic reactions release energy in the form of heat, light, or sound during the chemical process.
Q. What is formed when quicklime reacts with water?
A. Calcium carbonate
B. Calcium hydroxide
C. Calcium oxide
D. Calcium chloride
Answer: B
Explanation:
Quicklime reacts vigorously with water to form calcium hydroxide and releases a large amount of heat.
Q. Which of the following reactions involves exchange of ions between compounds?
A. Combination reaction
B. Double displacement reaction
C. Decomposition reaction
D. Oxidation reaction
Answer: B
Explanation:
In double displacement reactions, ions from two compounds exchange places to form new compounds.
Q. Rusting of iron requires the presence of:
A. Oxygen only
B. Water only
C. Oxygen and moisture
D. Nitrogen and sunlight
Answer: C
Explanation:
Iron rusts when it comes in contact with both oxygen and water. Moisture accelerates the corrosion process.
Q. Which of the following substances is commonly used to prevent oxidation in packaged foods?
A. Catalyst
B. Antioxidant
C. Acid
D. Indicator
Answer: B
Explanation:
Antioxidants slow down oxidation reactions in food products and help prevent spoilage due to rancidity.
Q. The chemical formula of calcium carbonate is:
A. CaCO₂
B. Ca₂CO₃
C. CaCO₃
D. Ca(CO₃)₂
Answer: C
Explanation:
Calcium carbonate contains one calcium atom, one carbon atom, and three oxygen atoms, represented by CaCO₃.
Q. Which gas supports combustion and is released during decomposition of potassium chlorate?
A. Nitrogen
B. Hydrogen
C. Oxygen
D. Carbon dioxide
Answer: C
Explanation:
Potassium chlorate decomposes on heating to release oxygen gas, which supports burning.
Q. A student notices bubbles forming when dilute acid is added to a metal sample. The bubbles most likely contain:
A. Chlorine gas
B. Oxygen gas
C. Hydrogen gas
D. Nitrogen gas
Answer: C
Explanation:
Most metals react with dilute acids to produce hydrogen gas along with a salt. The gas appears as bubbles during the reaction.
What You Will Learn in Chapter 1 Chemical Reactions and Equations
This chapter introduces students to the basic concepts of chemical changes and how reactions are represented using equations. It also explains how different types of reactions take place in everyday life.
Important Concepts Covered
- Chemical reactions
- Chemical equations
- Balanced chemical equations
- Combination reactions
- Decomposition reactions
- Displacement reactions
- Double displacement reactions
- Oxidation and reduction
- Corrosion
- Rancidity
How Practising Chapter 1 MCQs Improves Exam Performance
Many students read the chapter properly but still make mistakes in objective questions during exams. Practising MCQs regularly helps in understanding concepts in a much better way.
Benefits of Solving MCQs
| Benefit | How It Helps |
|---|---|
| Faster Revision | Covers multiple concepts quickly |
| Better Accuracy | Reduces silly mistakes |
| Concept Clarity | Strengthens fundamentals |
| Time Management | Improves solving speed |
| Exam Confidence | Reduces stress during tests |
| Pattern Understanding | Helps understand CBSE question trends |
MCQs are also useful for identifying weak areas before the exam. Students can revise important reactions, definitions, and concepts more effectively through practice questions.
Key Topics Included in Class 10 Science Chapter 1 MCQs
The questions in this chapter are generally asked from conceptual and reaction-based topics. Students should focus more on understanding reactions instead of memorising answers blindly.
| Topic | Important Areas |
|---|---|
| Chemical Equations | Writing reactions correctly |
| Balancing Equations | Applying law of conservation of mass |
| Combination Reactions | Formation of single products |
| Decomposition Reactions | Thermal, electrolytic, and photolytic reactions |
| Displacement Reactions | Reactivity-based replacement |
| Double Displacement Reactions | Exchange of ions |
| Oxidation and Reduction | Oxygen gain/loss and electron transfer |
| Corrosion | Rusting and prevention methods |
| Rancidity | Food spoilage and prevention |
Revision Notes for Chemical Reactions and Equations
What is a Chemical Reaction?
A process in which one or more substances change into new substances with different properties is called a chemical reaction.
What is a Chemical Equation?
A chemical equation is the symbolic representation of a chemical reaction using chemical formulas.
Example:
Mg + O₂ → MgO
What is a Balanced Chemical Equation?
A chemical equation in which the number of atoms of each element is equal on both sides is called a balanced chemical equation.
Types of Chemical Reactions
| Reaction Type | Example |
|---|---|
| Combination Reaction | CaO + H₂O → Ca(OH)₂ |
| Decomposition Reaction | 2AgCl → 2Ag + Cl₂ |
| Displacement Reaction | Zn + CuSO₄ → ZnSO₄ + Cu |
| Double Displacement Reaction | Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl |
Oxidation and Reduction
| Process | Meaning |
|---|---|
| Oxidation | Addition of oxygen or removal of hydrogen |
| Reduction | Removal of oxygen or addition of hydrogen |
Corrosion
The slow damage of metals due to moisture and air is called corrosion.
Example: Rusting of iron.
Rancidity
The oxidation of oils and fats causing unpleasant smell and taste is called rancidity.
Techniques to Solve Chemical Reactions and Equations MCQs Faster
Many students lose marks because of confusion between similar reactions or incorrect balancing. These simple techniques can improve accuracy in exams.
Follow These Tips:
- Read the complete reaction carefully before selecting the answer.
- Focus on keywords like oxidation, reduction, precipitate, and displacement.
- Check whether the equation is balanced properly.
- Observe state symbols carefully.
- Eliminate obviously incorrect options first.
- Revise NCERT examples and in-text questions.
- Practise assertion and reason questions regularly.
- Understand reaction logic instead of memorising answers.
Common Errors Students Make in Chapter 1 MCQs
Avoiding common mistakes can improve scores significantly in board exams.
| Common Mistake | Correct Approach |
|---|---|
| Incorrect balancing | Count atoms on both sides carefully |
| Confusing oxidation and reduction | Learn oxygen gain and loss properly |
| Ignoring state symbols | Observe solids, liquids, and gases carefully |
| Memorising without understanding | Focus on reaction concepts |
| Confusing reaction types | Practise identifying reaction patterns |
Conclusion
Chemical Reactions and Equations is one of the most important chapters in Class 10 Science because it introduces the core concepts of chemistry. Regular practice of Chemical Reactions and Equations Class 10 MCQs helps students strengthen concepts, improve accuracy, and prepare confidently for CBSE board exams. Focus on understanding reactions properly, revise important concepts regularly, and solve different types of MCQs to score better in the examination.
