NEET PYQ Redox Reactions PDF

1. In the reaction: Cr2O7^2- + 14H^+ + 6Fe^2+ → 2Cr^3+ + 6Fe^3+ + 7H2O Which species is the reducing agent? (a) Cr2O7^2- (b) H^+ (c) Fe^2+ (d) Cr^3+ Answer: (c) Fe^2+ 2. In the reaction: MnO4^- + 8H^+ + 5e^- → Mn^2+ + 4H2O The oxidation state of Mn changes from: (a) +7 to +2 (b) +2 to +7 (c) +4 to +...

1. In the reaction: Cr2O7^2- + 14H^+ + 6Fe^2+ → 2Cr^3+ + 6Fe^3+ + 7H2O Which species is the reducing agent? (a) Cr2O7^2- (b) H^+ (c) Fe^2+ (d) Cr^3+ Answer: (c) Fe^2+ 2. In the reaction: MnO4^- + 8H^+ + 5e^- → Mn^2+ + 4H2O The oxidation state of Mn changes from: (a) +7 to +2 (b) +2 to +7 (c) +4 to +2 (d) +2 to +4 Answer: (a) +7 to +2 3. Which of the following is a redox reaction? (a) NaCl + AgNO3 → AgCl + NaNO3 (b) CaCO3 → CaO + CO2 (c) 2Na + Cl2 → 2NaCl (d) NH4Cl → NH3 + HCl Answer: (c) 2Na + Cl2 → 2NaCl 4. In the reaction: Zn + CuSO4 → ZnSO4 + Cu Which element is oxidized? (a) Zn (b) Cu (c) S (d) O Answer: (a) Zn 5. The oxidation number of S in H2SO4 is: (a) +2 (b) +4 (c) +6 (d) -2 Answer: (c) +6 6. Which of the following is not a redox reaction? (a) 2H2 + O2 → 2H2O (b) CuO + H2 → Cu + H2O (c) Fe + S → FeS (d) CaCO3 → CaO + CO2 Answer: (d) CaCO3 → CaO + CO2 7. In the reaction: 2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 5Cl2 + 8H2O The oxidizing agent is: (a) KMnO4 (b) HCl (c) KCl (d) MnCl2 Answer: (a) KMnO4 8. The oxidation number of Cl in HClO4 is: (a) +1 (b) +3 (c) +5 (d) +7 Answer: (d) +7 9. Which of the following is a disproportionation reaction? (a) 2H2 + O2 → 2H2O (b) Cl2 + 2NaOH → NaCl + NaClO + H2O (c) 2KClO3 → 2KCl + 3O2 (d) 2Na + Cl2 → 2NaCl Answer: (b) Cl2 + 2NaOH → NaCl + NaClO + H2O 10. In the reaction: 2FeCl3 + H2S → 2FeCl2 + 2HCl + S The oxidation number of Fe changes from: (a) +3 to +2 (b) +2 to +3 (c) +1 to +2 (d) +2 to +1 Answer: (a) +3 to +2 11. Which of the following is a reducing agent? (a) KMnO4 (b) H2SO4 (c) HNO3 (d) H2S Answer: (d) H2S 12. The oxidation number of S in Na2S2O3 is: (a) +2 (b) +4 (c) +6 (d) +8 Answer: (b) +4 13. In the reaction: CuO + H2 → Cu + H2O Which element is reduced? (a) Cu (b) O (c) H (d) None of the above Answer: (a) Cu 14. The oxidation number of Cr in K2Cr2O7 is: (a) +2 (b) +3 (c) +6 (d) +7 Answer: (c) +6 15. Which of the following is not a characteristic of a redox reaction? (a) Oxidation and reduction occur simultaneously. (b) There is a change in oxidation number of one or more elements. (c) The reaction involves the transfer of electrons. (d) The reaction is always exothermic. Answer: (d) The reaction is always exothermic.