Can practising these questions improve exam performance?

Yes, regular practice improves conceptual clarity, accuracy, and confidence for the HSLC examination.

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions | Assam Eduverse

Q: Do these include previous year questions?

Yes, chapter-wise previous year questions are included to match HSLC exam trends.

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions are prepared to help students understand the fundamental concepts of chemical reactions in an exam-oriented manner. This page provides SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions along with previous year questions (PYQs) and important MCQs.

The SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions strictly follow the latest SEBA (ASSEB) syllabus for the academic session 2026–27. Since the HSLC exam pattern includes 45 MCQs, practising MCQs from this chapter is extremely important. These SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions include balanced equations, types of reactions, corrosion, rancidity, and numerical-based MCQs.

Students searching for HSLC Science Chapter 1 Chemical Reactions and Equations Important Questions or SEBA Class 10 Science Chapter 1 PYQs will find this resource highly useful.

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Questions with PYQs and MCQs

A. Previous Year Questions with Answers

Q1. Which of the following metals can replace copper from a solution of copper sulphate? —[HSLC 2015]
(i) Silver
(ii) Gold
(iii) Zinc
(iv) Mercury
Answer: (iii) Zinc

Q2. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above reaction is an example of a —[HSLC 2016, 2018]
(i) Combination reaction
(ii) Double displacement reaction
(iii) Decomposition reaction
(iv) Displacement reaction
Answer: (iv) Displacement reaction

Q3. What happens when dilute hydrochloric acid is added to iron fillings? —[HSLC 2017]
(i) Hydrogen gas and iron chloride are produced
(ii) Chlorine gas and iron hydroxide are produced
(iii) No reaction takes place
(iv) Iron salt and water are produced
Answer: (i) Hydrogen gas and iron chloride are produced

Q4. Decomposition of vegetable matters into compost is an example of which of the following class of reaction? —[HSLC 2023]
(i) Endothermic reaction
(ii) Exothermic reaction
(iii) Both
(iv) None of the above
Answer: (ii) Exothermic reaction

Q5. Which of the following does not involve a chemical reaction? [HSLC 2024]
(A) Digestion of food
(B) Respiration
(C) Burning of candle
(D) Melting of candle
Answer: (D) Melting of candle

Q6. Which of the following laws is satisfied by a balanced chemical reaction? [HSLC 2024]
(A) Conservation of momentum
(B) Conservation of mass
(C) Conservation of energy
(D) Conservation of density
Answer: (B) Conservation of mass

Q7. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
The above reaction is an example of which type of reaction? [2025]
(a) Displacement reaction
(b) Combination reaction
(c) Decomposition reaction
(d) Double displacement reaction
Answer: (a) Displacement reaction

Q8. 4Fe (s) + 3O₂ (g) →
Which option of the following shows the compound formed during the above reaction? [2025]
(a) 4FeO₃ (s)
(b) 12FeO (s)
(c) 3Fe₄O₂ (s)
(d) 2Fe₂O₃ (s)
Answer: (d) 2Fe₂O₃ (s)

Q9. Chemical reaction is not involved in [2025]
(a) burning of candle
(b) melting of candle
(c) digestion of food
(d) respiration
Answer: (b) melting of candle

B. Extra Question with Answers

Q1. When a magnesium ribbon is burnt in air, it forms —
(i) Magnesium nitride
(ii) Magnesium oxide
(iii) Magnesium sulphate
(iv) Magnesium chloride
Answer: (ii) Magnesium oxide.

Q2. Which of the following observations indicates that a chemical reaction has taken place?
(i) Change in state
(ii) Change in colour
(iii) Evolution of a gas
(iv) All of the above
Answer: (iv) All of the above.

Q3. The chemical equation Mg + O₂ → MgO is called a —
(i) Balanced chemical equation
(ii) Skeletal chemical equation
(iii) Double displacement equation
(iv) Thermal decomposition equation
Answer: (ii) Skeletal chemical equation.

Q4. The balanced chemical equation for the burning of magnesium in air is —
(i) Mg + O₂ → MgO₂
(ii) 2Mg + O₂ → 2MgO
(iii) Mg + O → MgO
(iv) 2Mg + 2O → 2MgO
Answer: (ii) 2Mg + O₂ → 2MgO.

Q5. In the reaction Zn + H₂SO₄ → ZnSO₄ + H₂, the gas evolved is —
(i) Oxygen
(ii) Nitrogen
(iii) Hydrogen
(iv) Carbon dioxide
Answer: (iii) Hydrogen.

Q6. When calcium oxide reacts with water, the reaction is —
(i) Endothermic
(ii) Exothermic
(iii) Displacement
(iv) Neutralisation
Answer: (ii) Exothermic.

Q7. The reaction CaO + H₂O → Ca(OH)₂ is an example of —
(i) Decomposition reaction
(ii) Combination reaction
(iii) Displacement reaction
(iv) Redox reaction
Answer: (ii) Combination reaction.

Q8. The green colour of ferrous sulphate crystals changes on heating because it decomposes to form —
(i) FeO
(ii) Fe₂O₃
(iii) Fe₃O₄
(iv) Fe(OH)₃
Answer: (ii) Fe₂O₃.

Q9. The brown fumes observed when lead nitrate is heated are of —
(i) Oxygen
(ii) Nitrogen
(iii) Nitrogen dioxide
(iv) Sulphur dioxide
Answer: (iii) Nitrogen dioxide.

Q10. White silver chloride turns grey in sunlight due to the formation of —
(i) Silver oxide
(ii) Silver metal
(iii) Silver sulphide
(iv) Silver nitrate
Answer: (ii) Silver metal.

Q11. The reaction 2AgCl(s) → 2Ag(s) + Cl₂(g) takes place in the presence of —
(i) Heat
(ii) Electricity
(iii) Sunlight
(iv) Catalyst
Answer: (iii) Sunlight.

Q12. In the electrolysis of water, the ratio of hydrogen to oxygen by volume is —
(i) 1 : 1
(ii) 1 : 2
(iii) 2 : 1
(iv) 8 : 1
Answer: (iii) 2 : 1.

Q13. In Activity 1.7, dilute sulphuric acid is added to water to —
(i) Change the colour of water
(ii) Increase the volume of gas
(iii) Make water conduct electricity
(iv) Cool the solution
Answer: (iii) Make water conduct electricity.

Q14. When an iron nail is dipped in copper sulphate solution, the blue colour of the solution fades because —
(i) Copper sulphate decomposes
(ii) Iron displaces copper
(iii) Iron forms iron oxide
(iv) Copper evaporates
Answer: (ii) Iron displaces copper.

Q15. The reaction Fe + CuSO₄ → FeSO₄ + Cu is an example of —
(i) Combination reaction
(ii) Decomposition reaction
(iii) Displacement reaction
(iv) Double displacement reaction
Answer: (iii) Displacement reaction.

Q16. The white precipitate formed when sodium sulphate reacts with barium chloride is —
(i) Sodium chloride
(ii) Barium chloride
(iii) Barium sulphate
(iv) Sodium sulphite
Answer: (iii) Barium sulphate.

Q17. A reaction in which two different ions are exchanged between reactants is called —
(i) Combination reaction
(ii) Displacement reaction
(iii) Double displacement reaction
(iv) Redox reaction
Answer: (iii) Double displacement reaction.

Q18. When copper powder is heated in air, the black substance formed is —
(i) Cu₂O
(ii) CuO
(iii) CuSO₄
(iv) CuCO₃
Answer: (ii) CuO.

Q19. If a substance gains oxygen during a reaction, it is said to be —
(i) Reduced
(ii) Neutralised
(iii) Oxidised
(iv) Displaced
Answer: (iii) Oxidised.

Q20. The process in which fats and oils are oxidised and their smell and taste change is called —
(i) Corrosion
(ii) Rancidity
(iii) Respiration
(iv) Combustion
Answer: (ii) Rancidity.

Q21. A magnesium ribbon burns in air with a dazzling white flame forming a white powder. The white powder is —
(i) Magnesium nitride
(ii) Magnesium oxide
(iii) Magnesium carbonate
(iv) Magnesium sulphide
Answer: (ii) Magnesium oxide.

Q22. When zinc granules react with dilute hydrochloric acid, the gas evolved burns with a ‘pop’ sound. The gas is —
(i) Oxygen
(ii) Hydrogen
(iii) Nitrogen
(iv) Carbon dioxide
Answer: (ii) Hydrogen.

Q23. When calcium oxide is mixed with water, the beaker becomes warm because the reaction is —
(i) Endothermic
(ii) Exothermic
(iii) Neutralisation
(iv) Double displacement
Answer: (ii) Exothermic.

Q24. Heating ferrous sulphate crystals produces a brown solid and gases. The brown solid formed is —
(i) FeO
(ii) Fe₂O₃
(iii) Fe₃O₄
(iv) Fe(OH)₃
Answer: (ii) Fe₂O₃.

Q25. On strong heating, lead nitrate decomposes to give lead oxide, nitrogen dioxide and —
(i) Hydrogen
(ii) Nitrogen
(iii) Oxygen
(iv) Sulphur dioxide
Answer: (iii) Oxygen.

Q26. When electric current is passed through water acidified with dilute sulphuric acid, bubbles are formed at both electrodes. The gas collected in larger amount is —
(i) Oxygen
(ii) Hydrogen
(iii) Nitrogen
(iv) Carbon dioxide
Answer: (ii) Hydrogen.

Q27. A white solid turns grey when kept in sunlight due to decomposition. The solid is —
(i) Silver nitrate
(ii) Silver chloride
(iii) Silver oxide
(iv) Silver sulphate
Answer: (ii) Silver chloride.

Q28. An iron nail placed in copper sulphate solution becomes brownish due to deposition of —
(i) Iron
(ii) Iron sulphate
(iii) Copper
(iv) Copper oxide
Answer: (iii) Copper.

Q29. Mixing aqueous sodium sulphate and barium chloride solutions produces a white precipitate of —
(i) Sodium chloride
(ii) Barium sulphate
(iii) Sodium sulphate
(iv) Barium chloride
Answer: (ii) Barium sulphate.

Q30. Passing hydrogen gas over heated copper(II) oxide changes the black solid to brown because copper(II) oxide is —
(i) Oxidised
(ii) Reduced
(iii) Neutralised
(iv) Displaced
Answer: (ii) Reduced.

Q31. A reaction in which a single product is formed from two or more reactants is called —
(i) Decomposition reaction
(ii) Combination reaction
(iii) Displacement reaction
(iv) Double displacement reaction
Answer: (ii) Combination reaction.

Q32. A reaction in which a single reactant breaks down to form two or more simpler substances is called —
(i) Combination reaction
(ii) Decomposition reaction
(iii) Redox reaction
(iv) Neutralisation reaction
Answer: (ii) Decomposition reaction.

Q33. When limestone is heated, it decomposes to form quick lime and —
(i) Oxygen
(ii) Hydrogen
(iii) Carbon dioxide
(iv) Carbon monoxide
Answer: (iii) Carbon dioxide.

Q34. The reaction in which heat is given out along with the formation of products is known as —
(i) Endothermic reaction
(ii) Exothermic reaction
(iii) Displacement reaction
(iv) Double displacement reaction
Answer: (ii) Exothermic reaction.

Q35. Respiration is considered an exothermic reaction because —
(i) Energy is absorbed
(ii) Energy is released
(iii) Oxygen is not used
(iv) Nitrogen is produced
Answer: (ii) Energy is released.

Q36. When a metal displaces another metal from its compound, the reaction is called —
(i) Combination reaction
(ii) Displacement reaction
(iii) Decomposition reaction
(iv) Precipitation reaction
Answer: (ii) Displacement reaction.

Q37. A reaction that produces an insoluble solid from two aqueous solutions is called —
(i) Combination reaction
(ii) Redox reaction
(iii) Precipitation reaction
(iv) Endothermic reaction
Answer: (iii) Precipitation reaction.

Q38. If a substance loses oxygen during a reaction, it is said to be —
(i) Oxidised
(ii) Reduced
(iii) Neutralised
(iv) Displaced
Answer: (ii) Reduced.

Q39. The reddish-brown coating formed on iron articles when exposed to moist air is known as —
(i) Rancidity
(ii) Corrosion
(iii) Reduction
(iv) Combustion
Answer: (ii) Corrosion.

Q40. Food containing fats and oils develops an unpleasant smell and taste due to —
(i) Reduction
(ii) Corrosion
(iii) Rancidity
(iv) Neutralisation
Answer: (iii) Rancidity.

Q41. Assertion (A): Magnesium ribbon should be cleaned before burning in air.
Reason (R): Magnesium ribbon forms a layer of magnesium oxide on its surface when exposed to air.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q42. Assertion (A): In a balanced chemical equation, the number of atoms of each element is equal on both sides.
Reason (R): Mass can neither be created nor destroyed in a chemical reaction.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q43. Assertion (A): When hydrogen gas is passed over heated copper(II) oxide, copper is formed.
Reason (R): Hydrogen removes oxygen from copper(II) oxide.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q44. Which of the following are exothermic reactions?
(i) Burning of natural gas
(ii) Respiration
(iii) Decomposition of calcium carbonate
(iv) Decomposition of vegetable matter into compost
(a) (i), (ii) and (iv)
(b) (i) and (iii)
(c) (iii) and (iv)
(d) (i), (ii), (iii) and (iv)
Answer: (a) (i), (ii) and (iv).

Q45. Which of the following are decomposition reactions?
(i) 2AgCl → 2Ag + Cl₂
(ii) CaCO₃ → CaO + CO₂
(iii) Fe + CuSO₄ → FeSO₄ + Cu
(iv) 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃
(a) (i), (ii) and (iv)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Answer: (a) (i), (ii) and (iv).

Q46. Match the following reactions with their types.

List I
A. CaO + H₂O → Ca(OH)₂
B. Zn + CuSO₄ → ZnSO₄ + Cu
C. Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
D. CaCO₃ → CaO + CO₂

List II

Decomposition reaction
Displacement reaction
Double displacement reaction
Combination reaction

(a) A-4, B-2, C-3, D-1
(b) A-1, B-2, C-4, D-3
(c) A-4, B-3, C-2, D-1
(d) A-2, B-4, C-3, D-1
Answer: (a) A-4, B-2, C-3, D-1.

Q47. Match the following processes with their descriptions.

List I
A. Corrosion
B. Rancidity
C. Oxidation
D. Reduction

List II

Gain of oxygen
Loss of oxygen
Deterioration of fats and oils
Metal attacked by moisture and air

(a) A-4, B-3, C-1, D-2
(b) A-3, B-4, C-2, D-1
(c) A-4, B-1, C-3, D-2
(d) A-2, B-3, C-1, D-4
Answer: (a) A-4, B-3, C-1, D-2.

Q48. Assertion (A): In a displacement reaction, a more reactive element displaces a less reactive element from its compound.
Reason (R): Zinc and lead can displace copper from copper sulphate solution.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q49. Which of the following reactions are redox reactions?
(i) 2Cu + O₂ → 2CuO
(ii) CuO + H₂ → Cu + H₂O
(iii) Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
(iv) ZnO + C → Zn + CO
(a) (i), (ii) and (iv)
(b) (i) and (iii)
(c) (iii) and (iv)
(d) (ii) only
Answer: (a) (i), (ii) and (iv).

Q50. Assertion (A): Silver bromide is used in black and white photography.
Reason (R): Silver bromide decomposes in sunlight to form silver and bromine.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q51. Assertion (A): Physical states are sometimes written in a chemical equation.
Reason (R): Writing physical states makes a chemical equation more informative.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q52. The notation (aq) written after a chemical formula indicates that the substance is —
(i) In gaseous state
(ii) In solid state
(iii) In aqueous solution
(iv) In molten state
Answer: (iii) In aqueous solution.

Q53. Which of the following reactions involve absorption of energy?
(i) Decomposition of calcium carbonate on heating
(ii) Decomposition of silver chloride in sunlight
(iii) Electrolysis of water
(iv) Burning of natural gas
(a) (i), (ii) and (iii)
(b) (i) and (iv)
(c) (ii) and (iv)
(d) (iv) only
Answer: (a) (i), (ii) and (iii).

Q54. In the reaction 3Fe + 4H₂O → Fe₃O₄ + 4H₂, the substance oxidised is —
(i) Hydrogen
(ii) Water
(iii) Iron
(iv) Fe₃O₄
Answer: (iii) Iron.

Q55. The gas that turns lime water milky is —
(i) Oxygen
(ii) Hydrogen
(iii) Carbon dioxide
(iv) Nitrogen
Answer: (iii) Carbon dioxide.

Q56. Match the following balanced equations with the form of energy supplied.

List I
A. CaCO₃ → CaO + CO₂
B. 2AgCl → 2Ag + Cl₂
C. 2H₂O → 2H₂ + O₂

List II

Light
Electricity
Heat

(a) A-3, B-1, C-2
(b) A-1, B-3, C-2
(c) A-2, B-1, C-3
(d) A-3, B-2, C-1
Answer: (a) A-3, B-1, C-2.

Q57. Assertion (A): Corrosion of iron is a serious problem.
Reason (R): Every year a large amount of money is spent to replace damaged iron.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A.

Q58. Which of the following statements are correct regarding oxidation?
(i) Gain of oxygen
(ii) Loss of hydrogen
(iii) Gain of hydrogen
(iv) Loss of oxygen
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Answer: (a) (i) and (ii).

Q59. In the reaction MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂, the substance reduced is —
(i) HCl
(ii) Cl₂
(iii) MnO₂
(iv) MnCl₂
Answer: (iii) MnO₂.

Q60. Assertion (A): In a double displacement reaction, there is an exchange of ions between reactants.
Reason (R): Such reactions often produce a precipitate.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (ii) Both A and R are true but R is not the correct explanation of A.

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions for HSLC Exam 2026–27

The SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions provided here are specially designed for HSLC students as per the latest SEBA (ASSEB) syllabus 2026–27. These questions include theory-based, equation balancing, reasoning-type, and MCQs aligned with the current exam pattern.

As per the updated HSLC structure, students must attempt 45 MCQs. Therefore, the SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions include conceptual MCQs along with short and long answer questions.

This chapter covers important concepts such as types of chemical reactions, balancing of chemical equations, oxidation and reduction, corrosion, and rancidity. Practising SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions helps students strengthen conceptual clarity and improve accuracy in numerical and theoretical answers.

These Class 10 Chemical Reactions and Equations Important Questions with MCQs are ideal for revision before the board examination. Regular practice of SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions builds confidence and reduces exam fear.

Frequently Asked Questions (FAQ)

1. Why is Chapter 1 Chemical Reactions and Equations important?

This chapter forms the foundation of Chemistry and includes balancing of equations, types of reactions, corrosion, and rancidity which are frequently asked in HSLC exams.

2. How many MCQs are asked in HSLC Science exam?

As per the latest HSLC exam pattern, students must answer 45 MCQs in the Science examination.

3. Are MCQs included in Chapter 1 important questions?

Yes, important conceptual MCQs from Chemical Reactions and Equations are included for exam-oriented preparation.

4. Are these questions based on the latest SEBA syllabus?

Yes, all questions are prepared strictly according to the latest SEBA (ASSEB) syllabus for 2026–27.

5. Do these include previous year questions (PYQs)?

Yes, chapter-wise previous year questions are included for better understanding of exam trends.

6. Which topics are covered in Chapter 1 important questions?

Topics include balancing equations, types of reactions, oxidation and reduction, corrosion, and rancidity.

7. Can practising these important extra questions improve exam performance?

Yes, regular practice improves conceptual clarity, accuracy in balancing equations, and confidence for the HSLC examination.

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Class 10 Chapter 1 Chemical Reactions and Equations PYQs

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions | Assam Eduverse

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Questions with PYQs and MCQs

Table of Contents

A. Previous Year Questions with Answers

B. Extra Question with Answers

SEBA Class 10 Science Chapter 1 Chemical Reactions and Equations Important Extra Questions for HSLC Exam 2026–27

Frequently Asked Questions (FAQ)

1. Why is Chapter 1 Chemical Reactions and Equations important?

2. How many MCQs are asked in HSLC Science exam?

3. Are MCQs included in Chapter 1 important questions?

4. Are these questions based on the latest SEBA syllabus?

5. Do these include previous year questions (PYQs)?

6. Which topics are covered in Chapter 1 important questions?

7. Can practising these important extra questions improve exam performance?

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