Class 10 Science Test Paper Chapter 1 Chemical reactions and equations | CBSE Board | Detailed Solutions & Marking Scheme
VEDANT IGNITE TEST SERIES – 2026
Class X – Science
Chapter 1: Chemical Reactions and Equations
Time Allowed: 1 Hour
Maximum Marks: 30
Section A – MCQs & Assertion Reason (1 × 7 = 7 marks)
1. When zinc granules are added to dilute hydrochloric acid, bubbles of a gas are observed. Which gas is produced?
(a) Oxygen (b) Hydrogen (c) Carbon dioxide (d) Nitrogen
2. Which observation confirms that a chemical reaction has taken place when iron nails are dipped in copper sulphate solution?
(a) Blue colour becomes darker (b) Brown deposit forms on iron nail (c) No change occurs (d) Solution becomes colourless
3. A white precipitate is formed when aqueous barium chloride reacts with sodium sulphate solution. The reaction is an example of:
(a) Combination reaction (b) Displacement reaction (c) Double displacement reaction (d) Decomposition reaction
4. Which of the following reactions represents oxidation?
(a) CuO + H₂ → Cu + H₂O
(b) Zn + H₂SO₄ → ZnSO₄ + H₂
(c) Cu → Cu²⁺ + 2e⁻
(d) Fe₂O₃ + CO → Fe + CO₂
5. Which condition is necessary to prevent rancidity in food items containing oils and fats?
(a) Exposure to sunlight (b) Storage in open containers (c) Storage in airtight containers (d) Addition of salt
Assertion–Reason Questions
6.
Assertion (A): Magnesium ribbon burns with a dazzling white flame when heated in air.
Reason (R): Magnesium reacts with oxygen to form magnesium oxide.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
7.
Assertion (A): A balanced chemical equation obeys the law of conservation of mass.
Reason (R): The number of atoms of each element remains the same on both sides of the equation.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Section B – Short Answer (2 × 4 = 8 marks)
8. A student observed that a black substance formed when copper powder was heated in air.
(i) Identify the black substance formed.
(ii) Write the balanced chemical equation for the reaction.
9. When calcium oxide reacts with water, a large amount of heat is released.
(i) Name the type of reaction.
(ii) Write the balanced chemical equation.
10. Write the balanced chemical equation for the reaction between iron and copper sulphate solution. Identify the type of reaction.
11. Give two observations which indicate that a chemical reaction has occurred during the reaction of sodium sulphate solution with barium chloride solution.
Section C – Competency Based Questions (3 × 2 = 6 marks)
12. A student kept an iron nail in blue copper sulphate solution overnight. The next day he observed that the solution became light green and a reddish brown coating appeared on the nail.
(i) Name the substance deposited on the nail.
(ii) Write the balanced chemical equation for the reaction.
(iii) Identify the type of reaction.
13. A student heated lead nitrate crystals in a test tube and observed brown fumes and a yellow residue.
(i) Name the gas evolved.
(ii) Write the balanced chemical equation.
(iii) Identify the type of reaction.
Section D – Long Answer (5 marks)
14. A student performed an experiment by adding dilute hydrochloric acid to zinc granules in a test tube.
(i) Write the balanced chemical equation for the reaction.
(ii) Name the gas evolved and describe the test to identify it.
(iii) Is this reaction a redox reaction? Justify your answer.
(iv) Identify which substance is oxidized and which is reduced.
Section E – Case Study (4 marks)
15. Read the passage carefully and answer the questions.
Rusting of iron is a common phenomenon observed when iron objects are exposed to moist air for a long period. Rust is a reddish-brown substance formed due to the reaction of iron with oxygen and moisture.
(a) Name the process responsible for rust formation. (1)
(b) Write the chemical formula of rust. (1)
(c) Explain any two methods to prevent rusting of iron. (2)
VEDANT IGNITE TEST SERIES – ANSWER KEY
Class 10 – Science (Chapter 1: Chemical Reactions and Equations)
Section A (1 × 7 = 7 marks)
1. (b) Hydrogen – 1 mark
2. (b) Brown deposit forms on iron nail – 1 mark
3. (c) Double displacement reaction – 1 mark
4. (c) Cu → Cu²⁺ + 2e⁻ – 1 mark
5. (c) Storage in airtight containers – 1 mark
6. (a) Both A and R are true and R is correct explanation – 1 mark
7. (a) Both A and R are true and R is correct explanation – 1 mark
Section B (2 × 4 = 8 marks)
8.
(i) Copper oxide (CuO) – 1 mark
(ii) 2Cu + O2 → 2CuO – 1 mark
9.
(i) Combination reaction (also exothermic) – 1 mark
(ii) CaO + H2O → Ca(OH)2 – 1 mark
10.
Fe + CuSO4 → FeSO4 + Cu – 1 mark
Type: Displacement reaction – 1 mark
11. (Any two observations)
• White precipitate formed – 1 mark
• Solution becomes cloudy/milky – 1 mark
Section C (3 × 2 = 6 marks)
12.
(i) Copper – 1 mark
(ii) Fe + CuSO4 → FeSO4 + Cu – 1 mark
(iii) Displacement reaction – 1 mark
(Marking: any 2 correct = 2 marks, all correct = 3 marks)
13.
(i) Nitrogen dioxide (NO2) – 1 mark
(ii) 2Pb(NO3)2 → 2PbO + 4NO2 + O2 – 1 mark
(iii) Thermal decomposition reaction – 1 mark
(Marking: any 2 correct = 2 marks, all correct = 3 marks)
Section D (5 marks)
14.
(i) Zn + 2HCl → ZnCl2 + H2 – 1 mark
(ii) Gas: Hydrogen – 1 mark
Test: Burns with pop sound – 1 mark
(iii) Yes, it is a redox reaction – 1 mark
Reason: Oxidation and reduction occur simultaneously
(iv)
Oxidized: Zn → Zn²⁺ – 0.5 mark
Reduced: H⁺ → H2 – 0.5 mark
Section E – Case Study (4 marks)
15.
(a) Rusting / Corrosion – 1 mark
(b) Fe2O3·xH2O – 1 mark
(c) (Any two methods, 1 mark each)
• Painting
• Oiling/greasing
• Galvanization
• Alloying (e.g., stainless steel)
MARKING NOTES (IMPORTANT FOR TEACHERS)
• Allow minor spelling errors if concept is correct
• Balanced equation must be chemically correct for full marks
• If equation correct but not balanced → deduct 0.5 mark
• In reasoning questions, keyword must be present (oxidation, reduction, displacement etc.)
• Step marking applicable in Section C, D, E
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