MCQs from CBSE Board (2009–2024)
1. (2024)
Which gas is used in packaging oil-containing food items?
A) CO₂ B) O₂ C) N₂ D) He
Answer: C (Nitrogen)
2. (2023)
Which of the following is not conveyed by a balanced chemical equation?
A) Physical states
B) Chemical formulas
C) Atomic/molecular ratios
D) Reaction feasibility
Answer: D
3. (2022)
The formula of lead sulfate is:
A) Pb₂SO₄ B) Pb(SO₄)₂ C) PbSO₄ D) Pb₂(SO₄)₃
Answer: C
4. (2021)
Which is a redox reaction?
A) CaCO₃ → CaO + CO₂
B) CuO + H₂ → Cu + H₂O
C) CaO + 2HCl → CaCl₂ + H₂O
D) NaOH + HCl → NaCl + H₂O
Answer: B
5. (2019)
In lead(II) nitrate decomposition, the coefficient of NO₂ is:
A) 1 B) 2 C) 3 D) 4
Answer: B
6. (2018)
Rust is chemically:
A) Hydrated ferrous oxide
B) Ferric oxide
C) Hydrated ferric oxide
D) None
Answer: C
7. (2017)
In water electrolysis, H₂:O₂ by volume is:
A) 1:2 B) 2:1 C) 8:1 by mass D) 1:2 by mass
Answer: A
8. (2015)
Silver chloride decomposes under:
A) Electricity B) Sunlight C) Heat D) Water
Answer: B
9. (2013)
CaCO₃ → CaO + CO₂ is a:
A) Combination B) Displacement C) Double displacement D) Decomposition
Answer: D
10. (2010)
Which reaction forms a white precipitate with AgNO₃?
A) KNO₃ B) AgNO₃ C) CuSO₄ D) Na₂SO₄
Answer: D (with AgNO₃ + Na₂SO₄ giving BaSO₄ white ppt)
- ZnO + CO → Zn + CO₂: Which is reduced?
A) ZnO B) CO C) CO₂ D) Zn
Answer: A - Which reaction forms a white precipitate?
A) KI + KNO₃ B) AgNO₃ + Na₂SO₄ C) CuSO₄ + AgNO₃ D) KNO₃ + CuSO₄
Answer: B - Process of cellular respiration is a type of:
A) Endothermic B) Reduction C) Redox D) Decomposition
Answer: C - Which is an exothermic process?
A) Electrolysis of water B) Cellular respiration C) Photosynthesis D) CaCO₃ → CaO + CO₂
Answer: B - Dissolution of KNO₃ in water is:
A) Oxidation B) Reduction C) Exothermic D) Endothermic
Answer: D - Colour of precipitate when K₂CrO₄ reacts with BaCl₂ is:
A) White B) Yellow C) Brown D) Red
Answer: B - Zn + CuSO₄ → ZnSO₄ + Cu is what type of reaction?
A) Combination B) Decomposition C) Displacement D) Double-displacement
Answer: C - CaCO₃ → CaO + CO₂ is:
A) Combination B) Displacement C) Double-displacement D) Decomposition
Answer: D - Which is not a balanced equation?
A) 2Mg + O₂ → 2MgO
B) NH₃ + HCl → NH₄Cl
C) NaOH + H₂SO₄ → Na₂SO₄ + H₂O
D) SO₂ + 2H₂S → 3S + 2H₂O
Answer: C - What cannot be changed while balancing equations?
A) Molecular formula B) Number of atoms C) Number of molecules D) Mass of reactants
Answer: A - Copper with dilute HNO₃ gives:
A) N₂ B) NO₂ C) H₂ D) NO
Answer: D - Catalyst in vanaspati ghee preparation is:
A) Al₂O₃ B) ZnO C) NaOH D) H₂SO₄
Answer: C - Which reaction is not thermal decomposition?
A) 2KClO₃ → 2KCl + 3O₂
B) ZnCO₃ → ZnO + CO₂
C) Fe₂(SO₄)₃ → Fe₂O₃ + 3SO₃
D) 2H₂O₂ → 2H₂O + O₂
Answer: D - In Y + 2HCl → Z + H₂ + ZnCl₂, Y =
A) Al B) Cu C) Na D) Zn
Answer: D - AgBr → Ag + Br₂ on sunlight exposure is an example of:
A) Oxidation B) Reduction C) Decomposition D) Photochemical
Answer: D - Y + 2HCl → Z + H₂ is a reaction where H₂ is:
A) Oxidizing agent B) Reducing agent C) Dehydrating agent D) Catalyst
Answer: B - Which of the following are double-displacement reactions?
- 1. Pb + CuCl₂ → PbCl₂ + Cu
- 2. Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
- 3. CO₂ + H₂O → Carbonic acid
A) 1&2 only B) 2&3 only C) 1&3 only D) All three
Answer: A
- Substance that prevents rancidity is:
A) Corrosion B) Rust C) Antioxidant D) Oxidation
Answer: C (common CBSE concept) - Which is an oxidizing agent?
A) LiAlH₄ B) KMnO₄ (acidified) C) K₂Cr₂O₇ (acidified) D) Both B & C
Answer: D - Mg ribbon burns in air with a _________________ reaction.
A) Combination B) Displacement C) Decomposition D) Double‑displacement
Answer: A
CBSE Class 10 Chemistry: Chapter 1 – Chemical Reactions and Equations 30 Multiple Choice Questions (MCQs) (Reflecting patterns from past CBSE Board Exams)
Instructions: Choose the correct option for each question.
- Question: Which of the following is a balanced chemical equation?
a) H2+O2→H2O
b) 2H2+O2→2H2O
c) H2+2O2→2H2O
d) 2H2+2O2→H2O
Answer: b) 2H2+O2→2H2O - Question: The reaction of ‘magnesium’ with air is a:
a) Endothermic reaction
b) Exothermic reaction
c) Reversible reaction
d) Substitution reaction
Answer: b) Exothermic reaction - Question: When dilute hydrochloric acid is added to granulated zinc, the gas evolved is:
a) Oxygen
b) Hydrogen
c) Carbon dioxide
d) Sulphur dioxide
Answer: b) Hydrogen - Question: Which of the following statements about the given reaction are correct?
3Fe(s)+4H2O(g)→Fe3O4(s)+4H2(g)
(i) Iron metal is getting oxidised.
(ii) Water is getting reduced.
(iii) Water is acting as reducing agent.
(iv) Water is acting as oxidising agent.
a) (i), (ii) and (iii)
b) (iii) and (iv)
c) (i), (ii) and (iv)
d) (ii) and (iv)
Answer: c) (i), (ii) and (iv) - Question: The chemical formula of rust is:
a) Fe2O3
b) Fe2O3.xH2O
c) Fe3O4
d) FeO.xH2O
Answer: b) Fe2O3.xH2O - Question: Which of the following is a displacement reaction?
a) CaO+CO2→CaCO3
b) NaOH+HCl→NaCl+H2O
c) Fe+CuSO4→FeSO4+Cu
d) CH4+2O2→CO2+2H2O
Answer: c) Fe+CuSO4→FeSO4+Cu - Question: When lead nitrate solution is mixed with potassium iodide solution, a precipitate is formed. The colour of this precipitate is:
a) Yellow
b) White
c) Blue
d) Brown
Answer: a) Yellow - Question: Which of the following are exothermic processes?
(i) Reaction of water with quick lime.
(ii) Dilution of an acid.
(iii) Evaporation of water.
(iv) Sublimation of camphor (crystals).
a) (i) and (ii)
b) (ii) and (iii)
c) (i) and (iv)
d) (ii) and (iv)
Answer: a) (i) and (ii) - Question: In the reaction CuO+H2→Cu+H2O, which substance is oxidized?
a) CuO
b) H2
c) Cu
d) H2O
Answer: b) H2 - Question: The reaction in which two compounds exchange their ions to form two new compounds is called:
a) Displacement reaction
b) Combination reaction
c) Double displacement reaction
d) Redox reaction
Answer: c) Double displacement reaction - Question: Which of the following gases can be used for the storage of a fresh sample of an oil for a long time?
a) Carbon dioxide or oxygen
b) Nitrogen or helium
c) Helium or oxygen
d) Nitrogen or oxygen
Answer: b) Nitrogen or helium - Question: Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
a) 1:1
b) 1:2
c) 2:1
d) 1:8
Answer: c) 2:1 - Question: When Ag is exposed to air, it gets a black coating of:
a) AgNO3
b) Ag2S
c) Ag2O
d) Ag2CO3
Answer: b) Ag2S - Question: Fatty foods become rancid due to the process of:
a) Reduction
b) Corrosion
c) Oxidation
d) Hydrogenation
Answer: c) Oxidation - Question: In the decomposition of lead (II) nitrate to give lead (II) oxide, nitrogen dioxide and oxygen gas, the coefficient of nitrogen dioxide (in the balanced equation) is:
a) 1
b) 2
c) 3
d) 4
Answer: d) 4 Balanced Equation: 2Pb(NO3)2(s)Heat2PbO(s)+4NO2(g)+O2(g) - Question: The reaction of quicklime with water to form slaked lime is an example of:
a) Decomposition reaction
b) Combination reaction
c) Displacement reaction
d) Redox reaction
Answer: b) Combination reaction - Question: A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’.
a) CaOCl2
b) Ca(OH)2
c) CaO
d) CaCO3
Answer: c) CaO - Question: Which of the following is an endothermic process?
a) Dilution of sulphuric acid
b) Condensation of water vapours
c) Sublimation of dry ice
d) Respiration in human beings
Answer: c) Sublimation of dry ice - Question: What happens when an iron nail is immersed in copper sulphate solution?
a) No reaction takes place.
b) The colour of the solution fades away.
c) The surface of iron nails acquires a black coating.
d) The colour of solution changes to green.
Answer: d) The colour of solution changes to green. - Question: A dilute ferrous sulphate solution was gradually added to the beaker containing acidified potassium permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?
a) KMnO4 is an oxidising agent, it oxidises FeSO4.
b) FeSO4 acts as an oxidising agent and oxidises KMnO4.
c) The colour disappears due to dilution; no reaction is involved.
d) KMnO4 is an unstable compound and decomposes in the presence of FeSO4 to a colourless compound.
Answer: a) KMnO4 is an oxidising agent, it oxidises FeSO4. - Question: The process of respiration is a:
a) Combination reaction
b) Decomposition reaction
c) Exothermic reaction
d) Endothermic reaction
Answer: c) Exothermic reaction - Question: When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is formed and sulphuric acid is produced. The reaction is an example of a:
a) Combination reaction
b) Displacement reaction
c) Double displacement reaction
d) Decomposition reaction
Answer: c) Double displacement reaction - Question: In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
a) 2H2(l)+O2(l)→2H2O(g)
b) 2H2(g)+O2(l)→2H2O(l)
c) 2H2(g)+O2(g)→2H2O(l)
d) 2H2(g)+O2(g)→2H2O(g)
Answer: c) 2H2(g)+O2(g)→2H2O(l) - Question: The reaction of NaOH with HCl to form NaCl and H2O is an example of:
a) Decomposition reaction
b) Double displacement reaction
c) Combination reaction
d) Displacement reaction
Answer: b) Double displacement reaction - Question: An element ‘X’ is more reactive than ‘Y’. When ‘X’ is added to a solution of ‘Y’, what will happen?
a) ‘Y’ will displace ‘X’.
b) ‘X’ will displace ‘Y’.
c) No reaction will occur.
d) Both ‘X’ and ‘Y’ will combine.
Answer: b) ‘X’ will displace ‘Y’. - Question: Which of the following is not a chemical change?
a) Burning of paper
b) Rusting of iron
c) Melting of ice
d) Digestion of food
Answer: c) Melting of ice - Question: To prevent the rancidity of oils and fats, which of the following is added to food items?
a) Antioxidants
b) Colouring agents
c) Preservatives that promote oxidation
d) Acids
Answer: a) Antioxidants - Question: A student performs an experiment to heat iron filings with dilute HCl and observes the evolution of a gas. The correct observation is:
a) The gas turns lime water milky.
b) The gas has a pungent smell.
c) The gas burns with a pop sound.
d) The gas is odourless and colourless.
Answer: c) The gas burns with a pop sound. - Question: When a solution of potassium iodide is added to a solution of lead nitrate, a yellow precipitate is formed. This is an example of a:
a) Combination reaction
b) Decomposition reaction
c) Displacement reaction
d) Precipitation reaction
Answer: d) Precipitation reaction - Question: Respiration is considered an exothermic reaction because:
a) Energy is absorbed
b) Glucose is oxidized to produce energy
c) Heat is absorbed during the process
d) It involves the formation of new compounds
Answer: b) Glucose is oxidized to produce energy
