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Chemical Reactions & Equations Test Class 10 — 40 Marks
Class 10Class 10 Science

Chemical Reactions & Equations Test Class 10 — 40 Marks

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PERIODIC TEST — Chapter Test (2026–27) | CLASS 10 | SUB: Science

Chapter 1 — Chemical Reactions and Equations | Max Marks: 40 | Time: 90 minutes

SectionMarksQuestionsTimeStrategy
A1212 MCQ15 minsQuick recall
B84 ×2M20 minsBrief
C124 ×3M30 minsDetailed
D82 ×4M Case20 minsAnalysis
Review5 mins

Syllabus: Balanced equations, types (combination/decomposition/displacement/double/precipitate), redox, corrosion, rancidity. Only NCERT scope for 2026–27.

Score: 0 / 40 — —

Section A — Multiple Choice (1 mark each)

Q1 · 1 mark

Q1. White precipitate BaSO4 forms in

📋 Marking Scheme: Correct option 1M
BaCl2+Na2SO4→BaSO4↓ white.
✅ Final Answer: (b) Double displacement (precipitation)
Q2 · 1 mark

Q2. 2Pb(NO3)2 → 2PbO + 4NO2 + O2 is

📋 Marking Scheme: 1M
Heat breaks lead nitrate.
✅ Final Answer: (b) Thermal decomposition
Q3 · 1 mark

Q3. Fe displaces Cu from CuSO4 because Fe is

📋 Marking Scheme: 1M
Reactivity series Fe>Cu.
✅ Final Answer: (b) more reactive
Q4 · 1 mark

Q4. Rancidity prevented by nitrogen flush because it

📋 Marking Scheme: 1M
Nitrogen is inert, prevents fat oxidation.
✅ Final Answer: (b) removes oxygen
Q5 · 1 mark

Q5. CuO + H2 → Cu + H2O: CuO is

📋 Marking Scheme: 1M
CuO loses O → reduced.
✅ Final Answer: (b) reduced
Q6 · 1 mark

Q6. Balanced: Fe + H2O → Fe3O4 + H2 is

📋 Marking Scheme: 1M
Balance Fe3, O4, H8 both sides.
✅ Final Answer: (a) 3Fe+4H2O → Fe3O4 +4H2
Q7 · 1 mark

Q7. 2AgCl → 2Ag + Cl2 needs sunlight — this is

📋 Marking Scheme: 1M
Light energy breaks AgCl.
✅ Final Answer: (a) photodecomposition
Q8 · 1 mark

Q8. White wash CaO + H2O → Ca(OH)2 + heat + CO2 → CaCO3 shine due to

📋 Marking Scheme: 1M
CaO+H2O combination then CO2 forms CaCO3 shiny.
✅ Final Answer: (c) combination then carbonation
Q9 · 1 mark

Q9. Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy is

📋 Marking Scheme: 1M
Energy released → exothermic.
✅ Final Answer: (c) exothermic
Q10 · 1 mark

Q10. Characteristic of chemical reaction includes

📋 Marking Scheme: 1M
All listed are signs.
✅ Final Answer: (b) all signs
Q11 · 1 mark

Q11. Which is double displacement?

📋 Marking Scheme: 1M
Two ions swap.
✅ Final Answer: (a) Na2SO4+BaCl2
Q12 · 1 mark

Q12. Corrosion black coating on silver is

📋 Marking Scheme: 1M
Silver with H2S forms Ag2S black.
✅ Final Answer: (a) Ag2S

Section B — Short Answer (2 marks each)

Q13 · 2 marks

Q13. What is balanced equation? Why balance? Give one example. [2M]

📋 Marking Scheme: • Definition 1M • Reason + example 1M
Balanced = equal atoms both sides. Mass conserved. Eg., 2Mg + O2 → 2MgO.
✅ Final Answer: Balanced conserves mass, example as above.
Q14 · 2 marks

Q14. Give one thermal and one photo decomposition reaction. [2M]

📋 Marking Scheme: • Thermal 1M • Photo 1M
Thermal: CaCO3 → CaO + CO2 (heat). Photo: 2AgCl → 2Ag + Cl2 (light).
✅ Final Answer: As above with conditions.
Q15 · 2 marks

Q15. Name the gas evolved when Zn reacts with acid, how to test? [2M]

📋 Marking Scheme: • Gas H2 1M • Pop test 1M
Zn + 2HCl → ZnCl2 + H2 ↑. Test: bring burning match, pop sound, burns with blue.
✅ Final Answer: H2, pop test.
Q16 · 2 marks · OR

Q16. Distinguish corrosion vs rancidity (2 points). [2M]

— OR —

Q16. Why do chips bags use nitrogen flush? [2M]

[Attempt any ONE]

📋 Marking Scheme: • Two correct distinctions 1M+1M | OR • Reason+method 1+1M

Option1: Corrosion rusts metals (Fe2O3); rancidity oxidises fats → foul smell. Prevention paint vs antioxidants/nitrogen.

Option2: Nitrogen inert, displaces O2, prevents fat oxidation, keeps chips fresh.

✅ Final Answer: As above.

Section C — Long Answer (3 marks each)

Q17 · 3 marks

Q17. Balance: (a) Ca(OH)2 + HNO3 → Ca(NO3)2 + H2O (b) BaCl2 + K2SO4 → BaSO4 + KCl [3M]

📋 Marking Scheme: • (a) balanced 1.5M • (b) balanced 1.5M
(a) Ca(OH)2 +2HNO3 → Ca(NO3)2 +2H2O. Check Ca1 N2 H4 O8 both.
(b) BaCl2 + K2SO4 → BaSO4 +2KCl.
✅ Final Answer: Balanced as above.
Q18 · 3 marks

Q18. Identify type + reason: (i) Burning Mg ribbon (ii) Electrolysis of water (iii) Fe+CuSO4 [3M]

📋 Marking Scheme: • Each correct type+reason 1M
(i) Combination 2Mg+O2→2MgO (ii) Electrolytic decomposition 2H2O→2H2+O2 (iii) Displacement Fe displaces Cu.
✅ Final Answer: As above.
Q19 · 3 marks · OR

Q19. Explain redox with CuO+H2 example, label oxidised/reduced. [3M]

— OR —

Q19. What is precipitation? Give two examples with precipitate colour. [3M]

📋 Marking Scheme: • Definition 1M • Example labelled 1M • Second point 1M

Opt1: CuO+H2→Cu+H2O, CuO loses O reduced, H2 gains O oxidised → redox both.

Opt2: Insoluble solid from double displacement. Eg., BaSo4 white, PbI2 yellow.

✅ Final Answer: As above.
Q20 · 3 marks · OR

Q20. Describe rancidity, effects, 4 prevention methods. [3M]

— OR —

Q20. Write three observations that indicate chemical reaction. [3M]

📋 Marking Scheme: • Definition 1M • Effects 1M • Prevention/observations 1M

Opt1: Fats oxidise → foul odour/taste. Prevent: antioxidant, air-tight, nitrogen, fridge.

Opt2: Change in state, colour, gas, precipitate, temp.

✅ Final Answer: As above.

Section D — Case-Based (4 marks each)

Q21 · 4 marks

Q21. Case: Student heats 2g FeSO4 crystals, observes brown solid + gases, smells. Related to decomposition.
(a) Equation? (1M) (b) Type + condition (1M) (c) Colour/odour reason (1M) (d) Other decomposition example with different condition (1M)

📋 Marking Scheme: (a)1M (b)1M (c)1M (d)1M
(a) 2FeSO4 → Fe2O3 + SO2 + SO3. (b) Thermal decomposition, heat. (c) Fe2O3 brown, SO2/SO3 pungent. (d) 2AgCl →2Ag+Cl2 photo (sunlight) or 2H2O→2H2+O2 electrolysis.
✅ Final Answer: As above with equations.
Q22 · 4 marks · OR

Q22. Case: Chips left open turn rancid, nitrogen bag stays fresh. Explain.
(a) Process name (1M) (b) Why nitrogen prevents (1M) (c) Two other preventions (1M) (d) Analogous corrosion example (1M)

— OR —

Q22. Case: White wash CaO + H2O → Ca(OH)2 then Ca(OH)2 + CO2 → CaCO3 shiny after 2 days.
(a) First reaction type (1M) (b) Second type (1M) (c) Why shiny (1M) (d) Balance both (1M)

📋 Marking Scheme: (a)1M (b)1M (c)1M (d)1M

Opt1: (a) Rancidity oxidation (b) Nitrogen inert displaces O2 (c) Air-tight, fridge/antioxidant (d) Rusting Fe2O3 corrosion analogous.

Opt2: (a) Combination CaO+H2O→Ca(OH)2 (b) Combination/carbonation (c) CaCO3 calcite shiny layer (d) Balanced as given.

✅ Final Answer: As above.
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