Class 10 Science Chemical Reactions and Equations MCQ
1. What is the name of the product formed when magnesium burns in air?
a) Magnesium carbonate
b) Magnesium oxide
c) Magnesium chloride
d) Magnesium nitrate
Answer: b
2. Which of these is a sign of a chemical reaction?
a) Change in size
b) Melting of ice
c) Change in colour
d) Breaking into pieces
Answer: c
3. In the equation: Mg + O₂ → MgO, what is MgO?
a) Reactant
b) Solvent
c) Product
d) Fuel
Answer: c
4. What type of reaction is this: CaO + H₂O → Ca(OH)₂?
a) Decomposition
b) Combination
c) Displacement
d) Redox
Answer: b
5. What is released in an exothermic reaction?
a) Water
b) Heat
c) Gas
d) Electricity
Answer: b
6. Which of these reactions is endothermic?
a) Burning of wood
b) Respiration
c) Photosynthesis
d) Combustion of fuel
Answer: c
7. Which one is a skeletal equation?
a) Mg + O₂ → MgO
b) 2Mg + O₂ → 2MgO
c) Ca + Cl₂ → CaCl₂
d) Zn + H₂SO₄ → ZnSO₄ + H₂
Answer: a
8. Why should a magnesium ribbon be cleaned before burning?
a) To remove dust
b) To look shiny
c) To remove oxide layer
d) To make it longer
Answer: c
9. What is the physical state of water in the equation: 3Fe + 4H₂O → Fe₃O₄ + 4H₂?
a) Liquid
b) Solid
c) Gas (steam)
d) Plasma
Answer: c
10. Which method is used to balance chemical equations?
a) Mirror method
b) Hit-and-trial method
c) LCM method
d) Addition method
Answer: b
11. In a displacement reaction, which element displaces the other?
a) Less reactive
b) More reactive
c) Same reactive
d) Neutral
Answer: b
12. What is formed when zinc reacts with sulphuric acid?
a) Zinc carbonate
b) Zinc nitrate
c) Zinc sulphate
d) Zinc oxide
Answer: c
13. The reaction: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃ is:
a) Combination
b) Decomposition
c) Displacement
d) Double displacement
Answer: b
14. What happens in decomposition reaction?
a) Two substances combine
b) One substance breaks down
c) No change
d) Electricity is produced
Answer: b
15. In the reaction: 2AgCl → 2Ag + Cl₂, what is the energy used?
a) Heat
b) Light
c) Sound
d) Electricity
Answer: b
16. Which gas is collected in double quantity during electrolysis of water?
a) Hydrogen
b) Oxygen
c) Nitrogen
d) Carbon dioxide
Answer: a
17. What is the colour of silver chloride before exposure to sunlight?
a) Grey
b) White
c) Black
d) Yellow
Answer: b
18. In a redox reaction, oxidation means:
a) Gain of hydrogen
b) Loss of oxygen
c) Gain of oxygen
d) No change
Answer: c
19. What is formed in rusting of iron?
a) Iron oxide
b) Iron sulphate
c) Iron nitrate
d) Iron chloride
Answer: a
20. Rancidity happens when:
a) Oil freezes
b) Food burns
c) Fats and oils oxidise
d) Water evaporates
Answer: c
21. Which of these is an example of a redox reaction?
a) Cu + O₂ → CuO
b) AgNO₃ + NaCl → AgCl + NaNO₃
c) CaO + H₂O → Ca(OH)₂
d) Fe + S → FeS
Answer: a
22. Which metal is more reactive than copper?
a) Silver
b) Gold
c) Iron
d) Mercury
Answer: c
23. In the reaction: Fe + CuSO₄ → FeSO₄ + Cu, what is Fe doing?
a) Forming rust
b) Displacing copper
c) Decomposing
d) Changing colour
Answer: b
24. A reaction in which two compounds exchange ions is called:
a) Combination
b) Double displacement
c) Oxidation
d) Decomposition
Answer: b
25. Which reaction is used in whitewashing?
a) CaO + H₂O → Ca(OH)₂
b) Na + Cl → NaCl
c) C + O₂ → CO₂
d) H₂ + O₂ → H₂O
Answer: a
