Chemistry Chapter-Wise Revision Test – MCQs

Scientia Tutorials · Board Exam Preparation

CBSE Class 10 Science: Chemistry Chapter-Wise Revision Test

Practise 30 carefully selected multiple-choice questions with instant answer checking and clear scientific explanations for the 2026–27 board examination preparation.

Class 10 · CBSE 30 MCQs 4 Chemistry Chapters Self-assessment

About This Revision Test

This practice test revises important concepts from NCERT Class 10 Science chemistry. Attempt each question, select one option, and check your answer. Open the explanation to revise the underlying concept, chemical reaction, or scientific principle.

Chapter 1Chemical Reactions and Equations · Q1–Q8

Chapter 2Acids, Bases and Salts · Q9–Q15

Chapter 3Metals and Non-metals · Q16–Q23

Chapter 4Carbon and Its Compounds · Q24–Q30

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Chapter 1: Chemical Reactions and Equations

1

Which of the following is a balanced chemical equation for the formation of water?

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Correct answer: B. A balanced chemical equation contains the same number of atoms of every element on both sides. In 2H₂ + O₂ → 2H₂O, both sides contain four hydrogen atoms and two oxygen atoms. This follows the law of conservation of mass: atoms are rearranged, not created or destroyed. Always balance equations using coefficients, not by changing chemical formula subscripts.

2

When lead nitrate is heated strongly, which observation is expected?

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Correct answer: C. Lead nitrate undergoes thermal decomposition when heated. It forms lead oxide, nitrogen dioxide and oxygen. Nitrogen dioxide is a brown gas, so brown fumes are observed.2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂This is a decomposition reaction because one compound breaks down into simpler substances due to heat.

3

Which type of reaction occurs when iron nails are placed in copper sulphate solution?

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Correct answer: A. Iron is more reactive than copper, so it displaces copper from copper sulphate solution. A reddish-brown deposit of copper forms on the nail, and the blue solution changes towards green due to iron(II) sulphate.Fe + CuSO₄ → FeSO₄ + CuA more reactive element displacing a less reactive element from its compound is called a displacement reaction.

4

Which of the following represents an oxidation reaction?

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Correct answer: D. In 2Cu + O₂ → 2CuO, copper combines with oxygen to form copper oxide. Addition of oxygen is a common definition of oxidation. In option A, copper oxide loses oxygen to form copper, so CuO is reduced, while hydrogen is oxidised to water. Oxidation and reduction often occur together in redox reactions.

5

Which reaction is an example of a combination reaction?

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Correct answer: B. In a combination reaction, two or more reactants combine to form a single product. Quicklime (calcium oxide) reacts with water to form slaked lime (calcium hydroxide).CaO + H₂O → Ca(OH)₂ + heatThe reaction releases heat, so it is also exothermic. This process is used in the preparation of slaked lime.

6

Why is silver chloride stored in dark-coloured bottles?

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Correct answer: C. Silver chloride is photosensitive. Exposure to sunlight causes it to decompose into silver and chlorine gas. The formation of metallic silver makes the white solid turn grey.2AgCl(s) → 2Ag(s) + Cl₂(g) (in sunlight)This is a photochemical decomposition reaction. Dark bottles reduce exposure to light and help preserve the compound.

7

Which process causes rancidity in food containing fats and oils?

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Correct answer: A. Rancidity occurs when fats and oils react with oxygen, producing substances that cause unpleasant smells and tastes. It can be slowed by storing food in airtight containers, refrigeration, using suitable antioxidants, and packing certain foods in nitrogen. These methods reduce oxidation or slow the reactions responsible for spoilage.

8

Which statement about an exothermic reaction is correct?

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Correct answer: D. Exothermic reactions release energy to their surroundings, commonly as heat. Respiration is an example because glucose reacts with oxygen and releases energy that cells use.C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energyIn contrast, an endothermic reaction absorbs energy from its surroundings.

Chapter 2: Acids, Bases and Salts

9

What colour does blue litmus paper turn in an acidic solution?

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Correct answer: B. Acids turn blue litmus red, whereas bases turn red litmus blue. Litmus is an acid-base indicator. In aqueous solution, acids produce hydrogen ions, which are present as hydronium ions (H₃O⁺). Indicators help identify whether a solution is acidic or basic, but litmus does not provide an exact pH value.

10

Which gas is produced when dilute hydrochloric acid reacts with zinc?

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Correct answer: C. Zinc reacts with dilute hydrochloric acid to form zinc chloride and hydrogen gas.Zn + 2HCl → ZnCl₂ + H₂↑Many metals above hydrogen in the reactivity series react with dilute acids to release hydrogen. The gas can be identified in a properly supervised laboratory by the characteristic pop sound when a small sample meets a flame.

11

A solution has a pH of 2. Which conclusion is correct?

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Correct answer: A. On the usual school-level pH scale, values below 7 indicate acidic solutions, pH 7 is neutral at about 25°C, and values above 7 indicate basic solutions. A pH of 2 indicates an acidic solution. The pH scale is logarithmic: a difference of one pH unit corresponds to a tenfold difference in hydrogen-ion activity, approximately in dilute aqueous solutions.

12

Which substance is commonly known as baking soda?

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Correct answer: D. Baking soda is sodium hydrogen carbonate, NaHCO₃. It is used in baking powder, certain antacids and some fire extinguishers. On heating, it releases carbon dioxide, which helps dough rise.2NaHCO₃ → Na₂CO₃ + H₂O + CO₂Washing soda is Na₂CO₃·10H₂O, while bleaching powder is commonly represented at this level as CaOCl₂.

13

What is the chemical formula of plaster of Paris?

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Correct answer: B. Plaster of Paris is calcium sulphate hemihydrate, CaSO₄·½H₂O. It is prepared by carefully heating gypsum, CaSO₄·2H₂O, to remove part of its water of crystallisation.CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂OWhen mixed with water, plaster of Paris sets into a hard mass as gypsum reforms.

14

Which salt is used to remove permanent hardness of water in the school-level NCERT context?

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Correct answer: C. Washing soda is sodium carbonate decahydrate, Na₂CO₃·10H₂O. Sodium carbonate reacts with dissolved calcium and magnesium ions to form insoluble carbonates, helping remove permanent hardness. Hard water does not lather easily with soap because calcium and magnesium ions form insoluble salts with soap.

15

Why does dry hydrogen chloride gas not change dry blue litmus paper to red?

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Correct answer: A. Hydrogen chloride ionises in water to produce hydronium ions, H₃O⁺, which account for its acidic properties. Without water, the dry gas does not provide the mobile aqueous ions needed to produce the usual litmus colour change.HCl + H₂O → H₃O⁺ + Cl⁻This demonstrates why the presence of water is important for the acidic behaviour of HCl.

Chapter 3: Metals and Non-metals

16

Which metal is stored under kerosene to prevent it from reacting rapidly with air and moisture?

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Correct answer: C. Sodium is highly reactive. It reacts vigorously with water and can react rapidly with oxygen and moisture in the air. Storing it under kerosene keeps it away from air and water. This is a safety precaution: sodium must never be handled casually or exposed to water.

17

Which of the following metals is the most appropriate conductor of electricity among these options?

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Correct answer: B. Silver has the highest electrical conductivity among metals under ordinary conditions. Copper is more commonly used for household wiring because it offers excellent conductivity at a lower cost. Metals conduct electricity because they contain mobile electrons that can move through the metallic structure.

18

Which metal can displace copper from an aqueous copper sulphate solution?

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Correct answer: D. Zinc is more reactive than copper, so it displaces copper from copper sulphate solution.Zn + CuSO₄ → ZnSO₄ + CuSilver, gold and platinum are less reactive than copper and cannot displace it from its salt solution under ordinary conditions. The reactivity series helps predict whether a displacement reaction will occur.

19

Which method is commonly used to prevent rusting of iron by coating it with zinc?

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Correct answer: A. Galvanisation involves coating iron or steel with zinc. The zinc coating blocks air and moisture and also provides sacrificial protection because zinc is more reactive than iron. Rusting is a form of corrosion that requires oxygen and moisture. Painting, oiling and greasing can also protect iron by preventing contact with air and water.

20

Why are ionic compounds generally solid at room temperature and have high melting points?

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Correct answer: C. Ionic compounds contain positive and negative ions arranged in a crystal lattice. Strong electrostatic attractions between oppositely charged ions require considerable energy to overcome, giving these compounds high melting points. Many ionic compounds conduct electricity when molten or dissolved in water because their ions can move, but not when solid because the ions are fixed in position.

21

Which of the following metals is generally extracted from its oxide by reduction with carbon in the school-level extraction examples?

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Correct answer: B. Zinc is less reactive than carbon and can be obtained by reducing zinc oxide with carbon at high temperature.ZnO + C → Zn + COHighly reactive metals such as sodium, potassium and calcium are generally extracted by electrolysis of their molten compounds. The extraction method depends on the metal's position in the reactivity series.

22

Which pair consists of amphoteric oxides?

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Correct answer: D. Aluminium oxide (Al₂O₃) and zinc oxide (ZnO) are amphoteric oxides. They react with both acids and bases. For example, zinc oxide reacts with hydrochloric acid to form zinc chloride and water. By contrast, many metal oxides are basic, while many non-metal oxides are acidic.

23

Which statement about metals and non-metals is generally correct?

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Correct answer: A. Metals generally lose one or more electrons to form positively charged ions called cations. Non-metals often gain electrons to form anions or share electrons in covalent bonds. These are general patterns rather than universal rules. Graphite, for example, is a non-metal that conducts electricity due to its structure and mobile electrons.

Chapter 4: Carbon and Its Compounds

24

What is the main reason carbon forms a very large number of compounds?

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Correct answer: C. Carbon is tetravalent, meaning it can form four covalent bonds. It also shows catenation, the ability to bond with other carbon atoms to form long chains, branched chains and rings. Together, these properties allow carbon to form a huge variety of stable compounds, including fuels, plastics, medicines and biological molecules.

25

Which is the correct molecular formula of ethane?

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Correct answer: B. Ethane has the molecular formula C₂H₆ and contains a single carbon-carbon bond. It is a saturated hydrocarbon belonging to the alkane family, which follows the general formula C_nH_2n+2 for open-chain alkanes. For n = 2, the formula is C₂H₆. Ethene (C₂H₄) has a double bond, and ethyne (C₂H₂) has a triple bond.

26

Which functional group is present in ethanol?

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Correct answer: D. Ethanol has the formula C₂H₅OH and contains the hydroxyl functional group (–OH), which characterises alcohols. Functional groups are specific atoms or groups of atoms that influence the chemical properties of organic compounds. The carboxyl group characterises carboxylic acids such as ethanoic acid, CH₃COOH.

27

What is the product formed when ethanol is oxidised under suitable conditions?

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Correct answer: A. Under suitable oxidising conditions, ethanol can be oxidised to ethanoic acid. Alkaline potassium permanganate or acidified potassium dichromate can act as oxidising agents in school-level chemistry.CH₃CH₂OH + 2[O] → CH₃COOH + H₂OThe symbol [O] represents oxygen supplied by the oxidising agent; it is not a separate molecular formula for the reagent.

28

What happens when ethanoic acid reacts with sodium hydrogen carbonate?

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Correct answer: C. Ethanoic acid reacts with sodium hydrogen carbonate to form sodium ethanoate, water and carbon dioxide. Effervescence occurs because carbon dioxide escapes as bubbles.CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂↑Acids reacting with metal carbonates or hydrogen carbonates generally produce a salt, water and carbon dioxide.

29

Which process produces an ester from an alcohol and a carboxylic acid?

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Correct answer: B. Esterification is the reaction between a carboxylic acid and an alcohol, generally in the presence of concentrated sulphuric acid, to form an ester and water.CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂OEthanoic acid reacts with ethanol to form ethyl ethanoate, which has a characteristic fruity smell. Esters are used in perfumes and flavouring applications.

30

Why does soap form scum when used with hard water?

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Correct answer: D. Hard water contains dissolved calcium and magnesium ions. These ions react with soap to form insoluble salts, known as scum. This wastes soap and reduces lather formation. Detergents generally work better than ordinary soaps in hard water because they do not form the same insoluble precipitates as readily.

Final Revision Checklist

After completing the test, revise these high-value concepts:

Balancing equations and identifying combination, decomposition, displacement and redox reactions.
Acid-base indicators, the pH scale, common salts and their chemical formulae.
The reactivity series, ionic compounds, corrosion and metal extraction.
Carbon tetravalency, catenation, homologous series and functional groups.
Important reactions of ethanol, ethanoic acid, soaps and detergents.

Exam preparation tip: practise writing balanced chemical equations from memory and explain why each reaction occurs. Always check the current CBSE syllabus and NCERT textbook for the 2026–27 academic session.