Looking for authentic SEBA Class 10 Science Chapter 1 (Chemical Reactions and Equations) MCQ solutions for the 2026–27 academic year? Access complete multiple-choice questions with correct options, detailed explanations, and quick objective revision notes to score 100% in your HSLC board exams.
MCQ
Q1. When milk sours in summer, the change is:
A) Physical
B) Chemical
C) Temporary
D) Reversible
Answer: B) Chemical
Q2. Rusting of iron is an example of:
A) Decomposition reaction
B) Combination reaction
C) Oxidation reaction
D) Double displacement reaction
Answer: C) Oxidation reaction
Q3. The products formed when magnesium burns in air are:
A) Mg and O₂
B) MgO
C) Mg(OH)₂
D) MgCO₃
Answer: B) MgO
Q4. The arrow (→) in a chemical equation shows:
A) Heat given out
B) Direction of reaction
C) Number of atoms
D) End of reaction
Answer: B) Direction of reaction
Q5. Which of the following is a combination reaction?
A) CaCO₃ → CaO + CO₂
B) Fe + CuSO₄ → FeSO₄ + Cu
C) CaO + H₂O → Ca(OH)₂
D) 2AgBr → 2Ag + Br₂
Answer: C) CaO + H₂O → Ca(OH)₂
Q6. A chemical reaction is recognized by:
A) Change in colour
B) Evolution of gas
C) Change in temperature
D) All of these
Answer: D) All of these
Q7. The balanced equation for magnesium burning in oxygen is:
A) Mg + O₂ → MgO
B) 2Mg + O₂ → 2MgO
C) Mg + 2O₂ → MgO₂
D) 2MgO → 2Mg + O₂
Answer: B) 2Mg + O₂ → 2MgO
Q8. Which of these reactions is endothermic?
A) Respiration
B) Combustion
C) Decomposition of CaCO₃
D) Neutralization
Answer: C) Decomposition of CaCO₃
Q9. Which one is a displacement reaction?
A) CaO + H₂O → Ca(OH)₂
B) Zn + CuSO₄ → ZnSO₄ + Cu
C) 2AgBr → 2Ag + Br₂
D) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
Answer: B) Zn + CuSO₄ → ZnSO₄ + Cu
Q10. A reaction in which heat is released is called:
A) Endothermic
B) Exothermic
C) Displacement
D) Redox
Answer: B) Exothermic
HSLC Science Chapter 1 Objective Questions
Q11. The general form of a decomposition reaction is:
A) A + B → AB
B) AB → A + B
C) AB + CD → AD + CB
D) A + BC → AC + B
Answer: B) AB → A + B
Q12. The reaction 2AgBr ⟶ 2Ag + Br₂ is:
A) Thermal decomposition
B) Photochemical decomposition
C) Electrolysis
D) Combustion
Answer: B) Photochemical decomposition
Q13. Which reaction involves exchange of ions?
A) Combination
B) Decomposition
C) Double displacement
D) Redox
Answer: C) Double displacement
Q14. Example of double displacement reaction:
A) Zn + CuSO₄ → ZnSO₄ + Cu
B) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
C) CaO + H₂O → Ca(OH)₂
D) CaCO₃ → CaO + CO₂
Answer: B) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
Q15. The white precipitate formed in Na₂SO₄ + BaCl₂ reaction is:
A) BaCO₃
B) BaSO₄
C) NaCl
D) Ba(OH)₂
Answer: B) BaSO₄
Q16. Oxidation involves:
A) Gain of hydrogen
B) Gain of oxygen
C) Loss of oxygen
D) Gain of electrons
Answer: B) Gain of oxygen
Q17. Reduction involves:
A) Gain of oxygen
B) Loss of hydrogen
C) Gain of hydrogen
D) Formation of water
Answer: C) Gain of hydrogen
Q18. In the reaction CuO + H₂ → Cu + H₂O, CuO is:
A) Oxidized
B) Reduced
C) Neutral
D) Catalyst
Answer: B) Reduced
Q19. MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂ shows:
A) Only oxidation
B) Only reduction
C) Both oxidation and reduction
D) Neutralization
Answer: C) Both oxidation and reduction
Q20. The mnemonic OIL RIG stands for:
A) Oxidation Is Loss, Reduction Is Gain
B) Oxygen Is Lost, Reaction Is Good
C) Oxidation Involves Loss, Reduction Involves Growth
D) None of these
Answer: A) Oxidation Is Loss, Reduction Is Gain
SEBA Class 10 Science Chapter 1 Multiple Choice Questions
Q21. Rusting is chemically represented as:
A) Fe + O₂ → FeO
B) Fe + H₂O + O₂ → Fe₂O₃·xH₂O
C) Fe + Cl₂ → FeCl₃
D) Fe₂O₃ → Fe + O₂
Answer: B) Fe + H₂O + O₂ → Fe₂O₃·xH₂O
Q22. The green coating on copper is:
A) Copper oxide
B) Basic copper carbonate
C) Copper sulphate
D) Copper chloride
Answer: B) Basic copper carbonate
Q23. The black coating on silver is:
A) AgCl
B) Ag₂O
C) Ag₂S
D) AgSO₄
Answer: C) Ag₂S
Q24. Which process prevents rusting?
A) Corrosion
B) Galvanization
C) Oxidation
D) Decomposition
Answer: B) Galvanization
Q25. Rancidity is caused by:
A) Reduction
B) Oxidation
C) Evaporation
D) Freezing
Answer: B) Oxidation
Q26. Which gas is filled in chips packets to prevent rancidity?
A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Helium
Answer: C) Nitrogen
Q27. The process where two or more reactants form one product is:
A) Decomposition
B) Combination
C) Displacement
D) Double displacement
Answer: B) Combination
Q28. Which reaction is exothermic?
A) CaO + H₂O → Ca(OH)₂
B) 2AgBr → 2Ag + Br₂
C) CaCO₃ → CaO + CO₂
D) Photosynthesis
Answer: A) CaO + H₂O → Ca(OH)₂
Q29. In the reaction Fe + CuSO₄ → FeSO₄ + Cu, the displaced element is:
A) Fe
B) Cu
C) SO₄
D) O₂
Answer: B) Cu
Q30. Law of Conservation of Mass states that:
A) Mass can be created
B) Mass can be destroyed
C) Mass is conserved during reactions
D) Mass always increases
Answer: C) Mass is conserved during reactions
Chemical Reactions and Equations Class 10 SEBA MCQ Notes
Q31. What is the purpose of cleaning the magnesium ribbon with sandpaper before burning it?
A. To make it shiny and attractive
B. To remove the oxide layer for easy burning
C. To shorten its length
D. To make it cool before burning
Answer: B. To remove the oxide layer for easy burning
Q32. Why is the magnesium ribbon rubbed with sandpaper before burning?
A. To make it shiny
B. To remove the oxide layer on its surface
C. To make it lighter
D. To increase its length
Answer: B. To remove the oxide layer on its surface
Q33. Why is the magnesium ribbon held with tongs during burning?
A. To prevent it from falling
B. To keep it away from the eyes
C. To protect the hand from heat and light
D. To collect the ash easily
Answer: C. To protect the hand from heat and light
Q34. What safety precaution should be taken while burning magnesium ribbon?
A. Close your eyes
B. Use gloves only
C. Wear eye protection and keep it away from eyes
D. Hold it with bare hands
Answer: C. Wear eye protection and keep it away from eyes
Q35. What happens when zinc granules are added to dilute hydrochloric acid or sulphuric acid?
A. No reaction takes place
B. A gas is evolved and bubbles are seen around the zinc granules
C. The solution turns blue
D. Zinc granules disappear instantly without any gas formation
Answer: B. A gas is evolved and bubbles are seen around the zinc granules
Q36. Which gas is produced when zinc reacts with dilute acids?
A. Oxygen
B. Nitrogen
C. Hydrogen
D. Carbon dioxide
Answer: C. Hydrogen
Q37. What is observed when you touch the conical flask or test tube after the reaction starts?
A. It becomes cold
B. It becomes hot
C. There is no change in temperature
D. It breaks immediately
Answer: B. It becomes hot
Q38. The increase in temperature of the flask indicates that the reaction is —
A. Endothermic
B. Exothermic
C. Neutral
D. Physical change only
Answer: B. Exothermic
Q39. Which of the following chemical equations correctly represents the reaction between zinc and dilute hydrochloric acid?
A. Zn + H₂SO₄ → ZnSO₄ + H₂↑
B. Zn + HCl → ZnCl₂ + H₂O
C. Zn + 2HCl → ZnCl₂ + H₂↑
D. Zn + 2H₂O → ZnO + 2H₂
Answer: C. Zn + 2HCl → ZnCl₂ + H₂↑
Q40. What precaution should be taken during this activity?
A. Do not use water
B. Handle the acid with care
C. Use concentrated acid for faster reaction
D. Heat the mixture before adding zinc
Answer: B. Handle the acid with care
Class 10 Science Chapter 1 MCQ Question Answer SEBA 2026-27
Q41. What happens when potassium iodide solution is added to lead nitrate solution?
A. No reaction occurs
B. A white precipitate is formed
C. A yellow precipitate is formed
D. The solution turns blue
Answer: C. A yellow precipitate is formed
Q42. What is the yellow precipitate formed in the reaction between lead nitrate and potassium iodide?
A. Lead sulphate (PbSO₄)
B. Lead iodide (PbI₂)
C. Potassium nitrate (KNO₃)
D. Lead oxide (PbO)
Answer: B. Lead iodide (PbI₂)
Q43. The reaction between lead nitrate and potassium iodide is an example of —
A. Combination reaction
B. Decomposition reaction
C. Double displacement (precipitation) reaction
D. Neutralization reaction
Answer: C. Double displacement (precipitation) reaction
Q44. Which of the following correctly represents the chemical equation for this reaction?
A. Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
B. Pb(NO₃)₂ + KI → Pb(NO₃) + KI₂
C. Pb(NO₃)₂ + K₂I → PbI + KNO₃
D. Pb(NO₃)₂ + 2KI → Pb(NO₃) + K₂I₂
Answer: A. Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
Q45. What type of change is observed in this reaction?
A. Physical change
B. Chemical change
C. Both physical and chemical change
D. No change
Answer: B. Chemical change
Q46. The formation of a yellow solid at the bottom of the test tube indicates —
A. Formation of a gas
B. Formation of a precipitate
C. Formation of a new colorless solution
D. Evaporation of the solvent
Answer: B. Formation of a precipitate
Q47. What happens when water is added slowly to calcium oxide (quick lime)?
A. No change takes place
B. A vigorous reaction occurs with release of heat
C. The solution becomes cold
D. Calcium oxide disappears without any reaction
Answer: B. A vigorous reaction occurs with release of heat
Q48. What is the product formed when calcium oxide reacts with water?
A. Calcium carbonate (CaCO₃)
B. Calcium hydroxide (Ca(OH)₂)
C. Calcium chloride (CaCl₂)
D. Calcium nitrate (Ca(NO₃)₂)
Answer: B. Calcium hydroxide (Ca(OH)₂)
Q49. What kind of change in temperature do you feel when touching the beaker after adding water to quick lime?
A. The beaker becomes cold
B. The beaker becomes hot
C. There is no change in temperature
D. The beaker cracks due to cooling
Answer: B. The beaker becomes hot
Q50. The reaction between calcium oxide and water is —
A. Endothermic reaction
B. Exothermic reaction
C. Neutralization reaction
D. Decomposition reaction
Answer: B. Exothermic reaction
SEBA Class 10 Science Chapter 1 MCQ Solutions
Q51. Which of the following correctly represents the chemical equation for the reaction?
A. CaO + H₂O → Ca(OH)₂ + heat
B. CaO + H₂O → CaO₂ + H₂
C. Ca + H₂O → Ca(OH)₂ + H₂
D. CaO + 2H₂O → Ca(OH)₄
Answer: A. CaO + H₂O → Ca(OH)₂ + heat
Q52. The slaked lime formed in this reaction is commonly used for —
A. Making cement and whitewashing walls
B. Cooling drinks
C. Preserving food
D. Producing hydrogen gas
Answer: A. Making cement and whitewashing walls
Q53. What is the color of ferrous sulphate (FeSO₄·7H₂O) crystals before heating?
A. White
B. Green
C. Blue
D. Yellow
Answer: B. Green
Q54. What happens when ferrous sulphate crystals are heated?
A. They melt into a blue liquid
B. They lose water and turn white
C. They lose water and turn brown due to decomposition
D. They sublimate without any change
Answer: C. They lose water and turn brown due to decomposition
Q55. Which gases are evolved when ferrous sulphate crystals are heated?
A. Sulphur dioxide (SO₂) and sulphur trioxide (SO₃)
B. Carbon dioxide (CO₂) and hydrogen (H₂)
C. Oxygen (O₂) and nitrogen (N₂)
D. Hydrogen sulphide (H₂S) and ammonia (NH₃)
Answer: A. Sulphur dioxide (SO₂) and sulphur trioxide (SO₃)
Q56. What type of chemical reaction takes place when ferrous sulphate is heated?
A. Combination reaction
B. Double displacement reaction
C. Decomposition reaction
D. Neutralization reaction
Answer: C. Decomposition reaction
Q57. Which solid substance is formed after heating ferrous sulphate crystals?
A. Ferric oxide (Fe₂O₃)
B. Ferrous oxide (FeO)
C. A mixture of ferric oxide (Fe₂O₃) and ferrous oxide (FeO)
D. Iron (Fe) metal
Answer: C. A mixture of ferric oxide (Fe₂O₃) and ferrous oxide (FeO)
Q58. Which of the following correctly represents the chemical equation for this reaction?
A. FeSO₄·7H₂O → Fe₂O₃ + SO₂ + SO₃ + H₂O
B. 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃
C. FeSO₄ → Fe + SO₂
D. 2FeSO₄·7H₂O → Fe₂O₃ + 2SO₂ + 2SO₃ + 14H₂O
Answer: D. 2FeSO₄·7H₂O → Fe₂O₃ + 2SO₂ + 2SO₃ + 14H₂O
Q59. What kind of odor is noticed when ferrous sulphate is heated?
A. Sweet smell
B. Rotten egg smell
C. Pungent smell of sulphur dioxide
D. No smell at all
Answer: C. Pungent smell of sulphur dioxide
🔬 Updated MCQ Guide Notice: This page features a full collection of SEBA Class 10 Science Chapter 1 (Chemical Reactions and Equations) Multiple Choice Questions (MCQs) with accurate options and step-by-step explanations, fully updated for the 2026–27 academic session in accordance with the latest revised Assam Board (SEBA) textbook.
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