Mock Test Paper – Chapter 1: Chemical Reactions and Equations


📝 Mock Test Paper – Chapter 1: Chemical Reactions and Equations

Subject: Science (Chemistry)
Class: 10
Board: CBSE
Max Marks: 30
Time: 1½ Hours

Section A – MCQs (1 × 5 = 5 Marks)

Q1. Which of the following is an example of a decomposition reaction?
a) CaO + H2O → Ca(OH)2
b) 2AgCl → 2Ag + Cl2
c) C + O2 → CO2
d) Zn + CuSO4 → ZnSO4 + Cu

Q2. Which law is followed while balancing a chemical equation?
a) Law of multiple proportion
b) Law of conservation of mass
c) Law of constant composition
d) Law of definite proportion

Q3. Identify the type of reaction:
Zn + 2HCl → ZnCl2 + H2

Q4. In the reaction: 2Mg + O2 → 2MgO, magnesium is:
a) Reduced
b) Oxidized
c) Neither oxidized nor reduced
d) Displaced

Q5. The brown gas evolved when lead nitrate crystals are heated is:
a) CO2
b) NO2
c) SO2
d) O2

Section B – Short Answer Questions (2 × 5 = 10 Marks)

Q6. Define a balanced chemical equation. Why should chemical equations be balanced?

Q7. Write balanced chemical equations for the following:
(i) Photosynthesis
(ii) Rusting of iron (word equation only)

Q8. A solution of substance X is used for whitewashing. Name substance X and write the chemical reactions involved.

Q9. Identify the type of reaction in each of the following and justify your answer:
(i) CaCO3 → CaO + CO2
(ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl

Q10. What happens when silver chloride is exposed to sunlight? Write the balanced equation. Mention one application of this reaction.

Section C – Long Answer Questions (5 × 3 = 15 Marks)

Q11. A student burns a magnesium ribbon in air. Answer the following:
(i) Why should the ribbon be cleaned before burning?
(ii) What is the type of reaction?
(iii) Write the balanced chemical equation with observation.

Q12. Explain any four characteristics of a chemical reaction with one balanced equation for each.

Q13. Write balanced chemical equations for the following reactions:
(i) Decomposition of calcium carbonate
(ii) Action of dilute hydrochloric acid on zinc
(iii) Reaction of sodium hydroxide with acetic acid

✅ Marking Scheme (30 Marks)

Section A (1 × 5 = 5 Marks)
Q1. b (1)
Q2. b (1)
Q3. Displacement reaction (1)
Q4. b – Oxidized (1)
Q5. b – NO2 (1)

Section B (2 × 5 = 10 Marks)
Q6. Definition (1) + reason (1) → 2
Q7. (i) 6CO2 + 6H2O → C6H12O6 + 6O2 (1)
(ii) Fe + O2 + H2O → Fe2O3·xH2O (1)
Q8. Name Ca(OH)2 (0.5), CaO + H2O → Ca(OH)2 (0.5), Ca(OH)2 + CO2 → CaCO3 + H2O (1) → 2
Q9. (i) Decomposition (1) (ii) Double displacement (1) → 2
Q10. 2AgCl → 2Ag + Cl2 (1) + application (1) → 2

Section C (5 × 3 = 15 Marks)
Q11. Cleaning reason (1) + type of reaction (1) + equation 2Mg + O2 → 2MgO (1) → 3
Q12. Any 4 characteristics with example equations (4 × 1.25 = 5) → 5
Q13. (i) CaCO3 → CaO + CO2 (1)
(ii) Zn + 2HCl → ZnCl2 + H2 (2 × 0.5 = 1)
(iii) NaOH + CH3COOH → CH3COONa + H2O (1) → 3

Total = 30 Marks 🎯


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