Class 10 Science MCQ Worksheet Chapter 1 Chemical Reactions and Equations | Detailed Solutions & Marking Scheme
VEDANT WORKSHEET SERIES - ACADEMIC
YEAR 2026-27
CLASS X | SCIENCE
CHAPTER 1:
CHEMICAL REACTIONS AND EQUATIONS
Time Allowed: 1
Hour | Maximum Marks: 30
SECTION A
(15 MCQs × 1 mark = 15 marks)
1. A student adds iron filings to copper sulphate
solution. After some time, the solution turns green. This indicates:
- a)
Formation of copper sulphate
- b) No
reaction has occurred
- c)
Displacement of copper by iron
- d)
Decomposition reaction
2. Which of the following represents a balanced chemical
equation?
- a) H2
+ O2 → H2O
- b)
2H2 + O2 → 2H2O
- c) H2
+ O2 → H2O2
- d)
2H2 + O → 2H2O
3. When calcium oxide reacts with water, heat is
released. This reaction is:
- a)
Endothermic
- b)
Exothermic
- c)
Displacement
- d)
Neutralisation
4. The reaction in which a single compound breaks into
two or more simpler substances is called:
- a)
Combination reaction
- b)
Decomposition reaction
- c)
Displacement reaction
- d)
Redox reaction
5. Which of the following is an example of a
precipitation reaction?
- a) Zn
+ HCl → ZnCl2 + H2
- b)
NaOH + HCl → NaCl + H2O
- c)
AgNO3 + NaCl → AgCl + NaNO3
- d)
CaCO3 → CaO + CO2
6. Identify the oxidising agent in the reaction:
Zn + CuSO4 → ZnSO4 + Cu
- a) Zn
- b) Cu
- c)
CuSO4
- d)
ZnSO4
7. Which of the following reactions involves both
oxidation and reduction?
- a)
CaO + H2O → Ca(OH)2
- b)
2H2O → 2H2 + O2
- c) Zn
+ CuSO4 → ZnSO4 + Cu
- d)
NaOH + HCl → NaCl + H2O
8. The gas evolved when zinc reacts with dilute
hydrochloric acid is:
- a)
Oxygen
- b)
Hydrogen
- c)
Carbon dioxide
- d)
Nitrogen
9. Which type of reaction is represented by:
A + BC → AC + B
- a)
Combination
- b)
Decomposition
- c)
Displacement
- d)
Double displacement
10. In electrolysis of water, water decomposes into
hydrogen and oxygen. This is:
- a)
Combination reaction
- b)
Thermal decomposition
- c)
Electrolytic decomposition
- d)
Displacement reaction
11. Rusting of iron is an example of:
- a)
Reduction
- b)
Oxidation
- c)
Neutralisation
- d)
Decomposition
12. Which observation confirms a chemical reaction has
occurred?
- a)
Change in shape
- b)
Change in state only
- c)
Evolution of gas and heat
- d) No
visible change*
13. The reaction between sodium sulphate and barium
chloride results in a white precipitate. The precipitate is:
- a)
NaCl
- b)
BaSO4
- c)
BaCl2
- d)
Na2SO4
14. Which reaction is endothermic?
- a)
Combustion of methane
- b)
Respiration
- c)
Decomposition of calcium carbonate
- d)
Formation of water
15. Which of the following statements is correct?
- a)
Reduction involves gain of oxygen
- b)
Oxidation involves loss of oxygen
- c)
Reduction involves gain of hydrogen
- d)
Oxidation involves gain of electrons
(15 Assertion-Reason Questions × 1 mark = 15 marks)
For Questions 16–30, choose the correct option:
A. Both A and R are true, R is correct explanation of A
B. Both A and R are true, R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
16. Assertion (A): Magnesium ribbon burns with a bright
white flame.
Reason (R): Magnesium reacts with oxygen to form magnesium oxide.
17. Assertion (A): Balanced chemical equations obey the
law of conservation of mass.
Reason (R): Total number of atoms of each element remains same on both sides.
18. Assertion (A): Decomposition reactions require
energy.
Reason (R): Bonds in compounds need energy to break.
19. Assertion (A): Iron displaces copper from copper
sulphate solution.
Reason (R): Iron is more reactive than copper.
20. Assertion (A): Double displacement reactions involve
exchange of ions.
Reason (R): They always produce a precipitate.
21. Assertion (A): Oxidation is loss of electrons.
Reason (R): Reduction is gain of electrons.
22. Assertion (A): All exothermic reactions release heat.
Reason (R): Energy is absorbed in exothermic reactions.
23. Assertion (A): Rusting of iron requires oxygen and
moisture.
Reason (R): Rust is hydrated iron(III) oxide.
24. Assertion (A): In a neutralisation reaction, salt and
water are formed.
Reason (R): It involves reaction between acid and base.
25. Assertion (A): Precipitation reactions are useful in
water purification.
Reason (R): Insoluble impurities can be removed by filtration.
26. Assertion (A): In the reaction Zn + HCl → ZnCl2 + H2,
zinc is oxidised.
Reason (R): Zinc loses electrons to form Zn2+ ions.
27. Assertion (A): Endothermic reactions feel cold.
Reason (R): They absorb heat from surroundings.
28. Assertion (A): Combustion reactions are always
exothermic.
Reason (R): They release heat and light energy.
29. Assertion (A): A chemical equation must be balanced.
Reason (R): Atoms are neither created nor destroyed in a reaction.
30. Assertion (A): In displacement reactions, less
reactive element replaces more reactive element.
Reason (R): Reactivity series determines displacement.
ANSWER KEY WITH DETAILED SOLUTIONS & MARKING SCHEME
CLASS X | SCIENCE | CHAPTER 1: CHEMICAL REACTIONS AND EQUATIONS
Marking Scheme:
• Each correct answer carries 1 mark
• No negative marking
• Total = 30 Marks
SECTION A – MCQs (15 Marks)
1. c) Displacement of copper by iron
Iron is more reactive than copper, so it displaces copper from CuSO4 solution. (Fe + CuSO4 → FeSO4 + Cu)
2. b) 2H2 + O2 → 2H2O
Balanced equation has equal number of atoms on both sides.
3. b) Exothermic
Heat is released when CaO reacts with water.
4. b) Decomposition reaction
A single compound breaks into simpler substances.
5. c) AgNO3 + NaCl → AgCl + NaNO3
Formation of insoluble AgCl (white precipitate).
6. c) CuSO4
Cu2+ ions gain electrons → reduction, hence oxidising agent.
7. c) Zn + CuSO4 → ZnSO4 + Cu
Oxidation (Zn → Zn2+) and reduction (Cu2+ → Cu) both occur.
8. b) Hydrogen
Zn + 2HCl → ZnCl2 + H2↑
9. c) Displacement
General form represents displacement reaction.
10. c) Electrolytic decomposition
Electric current causes decomposition.
11. b) Oxidation
Iron reacts with oxygen → rusting.
12. c) Evolution of gas and heat
Clear evidence of chemical reaction.
13. b) BaSO4
White insoluble precipitate formed.
14. c) Decomposition of calcium carbonate
Heat is absorbed → endothermic.
15. c) Reduction involves gain of hydrogen
Correct definition of reduction.
SECTION A – ASSERTION-REASON (15 Marks)
Correct Options:
A
Both true; burning Mg is reaction with oxygen forming MgO.A
Law of conservation of mass explained correctly.A
Energy is required to break bonds.A
Iron is more reactive → displaces copper.B
Both true, but not all double displacement reactions form precipitate.B
Both true but independent statements.C
Assertion true, Reason false (exothermic releases energy).A
Rusting requires O2 + moisture; rust is hydrated Fe2O3.A
Neutralisation produces salt + water.A
Precipitation helps remove impurities.A
Zinc loses electrons → oxidation.A
Endothermic absorbs heat → feels cold.A
Combustion always releases heat and light.A
Balanced equation follows conservation law.D
Assertion false (more reactive displaces less reactive), Reason true.
FINAL MARKING SUMMARY
| Section | Questions | Marks per Question | Total Marks |
|---|---|---|---|
| MCQs | 15 | 1 | 15 |
| AR | 15 | 1 | 15 |
| TOTAL | 30 | 30 |
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