Board Exam Practice — Chemical Reactions and Equations

Grade 10 Science — Board Exam Practice — Chemical Reactions and Equations: 25 practice questions with instant scoring and explanations.

1. Which of the following is a redox reaction?
2. In the reaction 2Fe₂O₃ + 3C → 4Fe + 3CO₂, carbon acts as:
3. What is the oxidation state of S in H₂SO₄?
4. Which statement is correct for the reaction: Zn + CuSO₄ → ZnSO₄ + Cu?
5. How many moles of O₂ are required to completely burn 2 moles of C₂H₆?
6. The balanced equation for the reaction of Fe with Cl₂ is:
7. What type of reaction is: CaCO₃ → CaO + CO₂?
8. In the reaction Na + ½O₂ → Na₂O, sodium acts as:
9. The oxidation state of N in NH₄⁺ is:
10. Which is NOT a chemical reaction?
11. How many grams of CO₂ are produced when 50g of CaCO₃ completely decomposes? (Ca=40, C=12, O=16)
12. The molecular weight of Fe₂O₃ is: (Fe=56, O=16)
13. In the reaction 3Fe + 4H₂O → Fe₃O₄ + 4H₂, which is the reducing agent?
14. What is the coefficient of O₂ when the equation C₂H₅OH + O₂ → CO₂ + H₂O is balanced?
15. Which reaction represents a decomposition reaction?
16. The oxidation state of Cr in K₂Cr₂O₇ is:
17. In a redox reaction, the substance that loses electrons is:
18. What happens to the oxidation state of carbon when CH₄ is converted to CO₂?
19. In the reaction: Mg + 2HCl → MgCl₂ + H₂, what is the role of Mg?
20. The balanced equation for combustion of CH₄ is:
21. If 48g of Mg reacts completely with O₂ to form MgO, how many grams of MgO are formed? (Mg=24, O=16)
22. Which of the following statements is true about exothermic reactions?
23. The oxidation state of P in H₃PO₄ is:
24. In the reaction C + 2H₂SO₄(conc.) → CO₂ + 2SO₂ + 2H₂O, which element is oxidized?
25. What is the limiting reactant when 24g of Fe reacts with 6g of O₂ to form Fe₃O₄? (Fe=56, O=16)