CBSE Class 10 Science • Chapter 1 • Revision 2026
Chemical Reactions and Equations Class 10 Worksheet
Download the Chemical Reactions and Equations Class 10 worksheet with answers for CBSE Science self-revision and practice. Revise balanced chemical equations, reaction types, oxidation, reduction, corrosion and rancidity. Use the worked examples, MCQs and extra questions below to strengthen your understanding before attempting the worksheet PDF.
Chemical reactions explain changes such as rusting iron, burning magnesium and the formation of an insoluble solid when two solutions are mixed. In Class 10 Science Chapter 1 Chemical Reactions and Equations, you learn to identify new substances and represent their formation using chemical equations.
A worksheet on Chemical Reactions and Equations Class 10 is useful when you practise actively: write the equation, balance it, identify the reaction and explain the observation. Checking answers afterwards helps you recognise whether a mistake came from a formula, an atom count or an incomplete explanation.
How to Use This Practice Resource
- Review the short notes and reaction chart below.
- Attempt the downloadable worksheet without checking answers.
- Compare your equations and explanations with the answers.
- Correct mistakes and solve similar questions again.
The examples on this page provide additional practice alongside the worksheet; they are not presented as a list of its exact contents.
Chemical Reactions and Equations Class 10 Short Notes
A chemical reaction forms new substances with different properties. Reactants appear on the left of the arrow, and products appear on the right. A word equation names the substances, while a chemical equation uses their symbols and formulas.
A reaction may involve gas evolution, a colour change, a temperature change or precipitate formation. Interpret these observations in context: bubbles during boiling water result from a physical change, so bubbles alone do not prove that a chemical reaction occurred.
State symbols make an equation more informative: (s) means solid, (l) liquid, (g) gas and (aq) dissolved in water. Heating, sunlight or electricity should also be stated when relevant.
Chemical Reactions and Equations Class 10 Balancing Questions
Balancing chemical equations means making the number of atoms of each element equal on both sides. Change the coefficients placed before formulas, never the subscripts within formulas. This preserves the identity of the substances and follows the law of conservation of mass.
Worked Example: Aluminium Reacting with Oxygen
Start with the skeletal equation:
Al + O2 → Al2O3
Make the oxygen count equal to 6 on both sides:
Al + 3O2 → 2Al2O3
Balance aluminium:
4Al + 3O2 → 2Al2O3
Final check: each side contains 4 aluminium atoms and 6 oxygen atoms.
Balancing Practice with Answers
Try each equation before opening the answer. Count every element, including atoms inside brackets.
1. Balance Zn + HCl → ZnCl2 + H2
Zn + 2HCl → ZnCl2 + H2
Each side contains 1 zinc atom, 2 hydrogen atoms and 2 chlorine atoms.
2. Balance Fe + H2O → Fe3O4 + H2
3Fe + 4H2O → Fe3O4 + 4H2
Each side contains 3 iron atoms, 8 hydrogen atoms and 4 oxygen atoms.
This reaction involves steam under suitable heating conditions.
3. Balance Pb(NO3)2 → PbO + NO2 + O2
2Pb(NO3)2
→ 2PbO + 4NO2 + O2
, on heating.
Each side contains 2 lead atoms, 4 nitrogen atoms and 12 oxygen atoms.
Chemical Reaction Types: Quick Revision Chart
| Type | How to Recognise It | Example |
|---|---|---|
| Combination | Two or more reactants form one product. | CaO + H2O → Ca(OH)2 |
| Thermal decomposition | A substance breaks down on heating. | CaCO3 → CaO + CO2, on heating. |
| Photochemical decomposition | Light causes a substance to break down. | 2AgCl → 2Ag + Cl2, in sunlight. |
| Electrolytic decomposition | Electricity causes decomposition. | 2H2O → 2H2 + O2, using electricity. |
| Displacement | A more reactive element replaces a less reactive element. | Fe + CuSO4 → FeSO4 + Cu |
| Double displacement and precipitation | Ions exchange and an insoluble solid forms. | Na2SO4 + BaCl2 → BaSO4 + 2NaCl |
| Redox | Oxidation and reduction occur together. | CuO + H2 → Cu + H2O, on heating. |
One Reaction Can Have More Than One Classification
Calcium oxide reacting with water is a combination reaction because one product forms. It is also exothermic because heat is released. Reaction pattern and energy change describe different aspects of the same process.
Chemical Reactions and Equations Class 10 MCQ Questions with Answers
1. Which change is allowed while balancing an equation?
A. Changing an element’s symbol
B. Changing a compound’s subscripts
C. Changing coefficients before formulas
D. Removing a reactant
Answer: C. Coefficients change the quantities represented without changing the substances.
2. What forms when barium chloride and sodium sulphate solutions are mixed?
A. A white barium sulphate precipitate
B. A brown copper deposit
C. Hydrogen gas
D. Black copper oxide
Answer: A. Barium sulphate is insoluble in water and separates as a white solid.
3. Which substance is reduced in CuO + H2 → Cu + H2O?
A. H2
B. CuO
C. H2O
D. Neither reactant
Answer: B. Copper oxide loses oxygen and forms copper.
Class 10 Competency-Based and Case Study Questions
Case Study: An Iron Nail in Copper Sulphate Solution
A student places a clean iron nail in blue copper sulphate solution. After some time, a reddish-brown deposit appears on the nail and the solution changes towards pale green.
- Identify the reddish-brown substance.
- Write the balanced equation.
- Name the reaction type.
- Explain why copper would not displace iron from iron sulphate.
Answers:
The deposit is copper.
Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s).
It is a displacement reaction.
Iron is more reactive than copper; copper cannot displace iron
under the usual conditions of this experiment.
Chemical Reactions and Equations Class 10 competency-based questions ask you to use evidence rather than recall a definition alone. Link the observation to the product formed and explain the scientific reason. This approach also helps with activity-based questions and short-answer questions.
Chemical Reactions and Equations Class 10 Extra Questions with Answers
Why is respiration considered exothermic?
The breakdown of glucose during respiration releases energy.
Its overall equation can be represented as:
C6H12O6 + 6O2
→ 6CO2 + 6H2O + energy.
Identify oxidation, reduction and the agents in CuO + H2 → Cu + H2O.
Hydrogen gains oxygen, so it is oxidised. Copper oxide loses oxygen, so it is reduced. Hydrogen is the reducing agent, while copper oxide is the oxidising agent.
Explain corrosion and rancidity with examples.
Corrosion is deterioration of metals through reactions with their surroundings, such as rusting iron. Oxidative rancidity occurs when fats and oils react with oxygen, producing unpleasant smells and tastes. Painting protects iron, while airtight storage helps delay rancidity.
Using the Worksheet as a Chapter Test
Use this Chemical Reactions and Equations practice worksheet for self-study after revising the chapter. Attempt questions in one sitting and check the answers afterwards. Review balancing, reaction identification and reasoning separately so you know which skill needs more practice.
For further preparation, solve your NCERT intext questions and exercise questions. Consult Chemical Reactions and Equations Class 10 NCERT solutions after attempting them yourself. When practising previous year questions, use papers with a verified examination year rather than assuming every “board-style” question is an actual PYQ.
Related Class 10 Science Resources
Review concepts through the CBSE Class 10 Science notes collection before returning to questions you found difficult.
Explore the CBSE Class 10 Science worksheet collection for chapter-wise Chemistry, Biology and Physics practice.
Chemical Reactions and Equations Class 10 Frequently Asked Questions
How should I practise the worksheet PDF with answers?
Attempt it first without referring to answers. Then check formulas, coefficients, observations and explanations. Correct the reason behind each mistake before repeating the question.
Why is magnesium ribbon cleaned before burning?
Cleaning removes the surface coating, commonly described in school answers as magnesium oxide. This exposes the metal and allows it to react with oxygen more readily.
What is the easiest way to balance chemical equations?
Write correct formulas, count atoms and adjust coefficients systematically. Balance an element appearing in fewer compounds first when convenient, then recount every element. Never alter subscripts to force a balance.
What is the difference between a skeletal and a balanced equation?
A skeletal equation shows reactants and products but may have unequal atom counts. A balanced equation has equal counts of each element on both sides.
Why does silver chloride turn grey in sunlight?
Silver chloride decomposes in sunlight to form metallic
silver and chlorine. The silver gives the grey appearance:
2AgCl(s) → 2Ag(s) + Cl2(g).
What is the brown gas formed when lead nitrate is heated?
It is nitrogen dioxide, NO2. Lead nitrate decomposes
to form lead oxide, nitrogen dioxide and oxygen:
2Pb(NO3)2
→ 2PbO + 4NO2 + O2.
Is every double displacement reaction a precipitation reaction?
No. Precipitation specifically requires an insoluble solid to form. Other double displacement reactions, including many neutralisation reactions, need not produce a precipitate.
Why are some food packets filled with nitrogen?
Nitrogen flushing reduces oxygen around the food. This slows oxidation of fats and oils and helps delay rancidity.
How do I remember oxidising and reducing agents?
Name the agent by what it does to the other substance. An oxidising agent causes oxidation and is itself reduced. A reducing agent causes reduction and is itself oxidised.
Which Chemical Reactions and Equations questions should I practise for 2026 revision?
Practise balancing, reaction types, experimental observations, oxidation and reduction, and everyday applications. Include MCQs, short answers and case-based questions. Use your prescribed textbook and current board guidance to organise preparation.
Does this chapter have a fixed individual marks weightage?
Do not assume a fixed chapter mark allocation from unofficial keyword lists or predictions. Consult the applicable CBSE assessment guidance and sample paper, and prepare the full prescribed content.
How can I improve reaction-based answers?
Include the correct balanced equation, relevant conditions, reaction type and observation when asked. Keep the explanation specific: name the substance formed and explain the change rather than writing only “a reaction occurs”.
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