This quiz works best with JavaScript enabled. Home > Cbse > Class 11 > Science > Chemistry Part Ii > Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions – Quiz 6 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 6 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. Is calcium oxidized or reduced in the following reaction? 2CaO$\rightarrow$ 2Ca + O$_{2}$ A) Oxidized. B) Reduced. C) None of these. D) None of the above. Show Answer Correct Answer: C) None of these. 2. Given the balanced ionic equation representing a reaction:2Al(s) + 3Cu$^{2+}$(aq) $\rightarrow$ 2Al$^{3+}$(aq) + 3Cu(s) Which half-reaction represents the reduction that occurs? A) Cu $\rightarrow$ Cu$^{2+}$ + 2e$^{-}$. B) Al$^{3+}$ + 3e$^{-}$ $\rightarrow$ Al. C) Cu$^{2+}$ + 2e$^{-}$$\rightarrow$ Cu. D) Al $\rightarrow$ Al$^{3+}$ + 3e$^{-}$. Show Answer Correct Answer: C) Cu$^{2+}$ + 2e$^{-}$$\rightarrow$ Cu. 3. What role does the electrolyte play in a fuel cell? A) It stores electrical energy for later use. B) It acts as a barrier to electron flow. C) It provides a medium for ion exchange. D) It increases the electrical resistance of the cell. Show Answer Correct Answer: C) It provides a medium for ion exchange. 4. What is the oxidation state of zinc in Zn(OH)$_{4}$$^{2-}$ A) +1. B) +2. C) 0. D) -1. Show Answer Correct Answer: B) +2. 5. What is the oxidation number of carbon in NaHCO3? A) +6. B) +4. C) +1. D) -4. Show Answer Correct Answer: B) +4. 6. What happens to the oxidising agent in an oxidation-reduction reaction? A) It is reduced as it loses electrons. B) It is oxidised as it gains electrons. C) It is oxidised as it loses electrons. D) It is reduced as it gains electrons. Show Answer Correct Answer: D) It is reduced as it gains electrons. 7. In a redox reaction, spectator ions ..... A) Become oxidised. B) Become reduced. C) Remain unchanged. D) None of the above. Show Answer Correct Answer: C) Remain unchanged. 8. An element's oxidation numbers remain the same during a reaction. What happened to that element? A) It was oxidized. B) It was reduced. C) It was both oxidized and reduced. D) It was neither oxidized nor reduced. Show Answer Correct Answer: D) It was neither oxidized nor reduced. 9. What does the term 'oxidizing agent' refer to? A) A substance that is oxidized. B) A substance that is reduced. C) A substance that gains electrons. D) A substance that loses electrons. Show Answer Correct Answer: C) A substance that gains electrons. 10. What happens to the oxidation number of sulfur in the reaction 2Cu2O + Cu2S $\rightarrow$ 6Cu + SO2? A) It becomes zero. B) It increases. C) It remains the same. D) It decreases. Show Answer Correct Answer: B) It increases. 11. In the balanced chemical reaction, IO$_{3}$$^{-}$ + a I$^{-}$ + b H$^{+}$ $\rightarrow$ c H$_{2}$O + d I$_{2, }$a, b, c and d are: A) 5, 3, 6, 3. B) 5, 6, 5, 5. C) 5, 5, 3, 6. D) 5, 6, 3, 3. Show Answer Correct Answer: D) 5, 6, 3, 3. 12. What chemical process must always accompany a reduction process A) Salt formation. B) Water formation. C) Neutralization. D) Oxidation. Show Answer Correct Answer: D) Oxidation. 13. Determine the oxidation number of iron in FeCl$_{3}$. A) +3. B) +2. C) 0. D) +1. Show Answer Correct Answer: A) +3. 14. What is oxidation number of P in K$_{3}$PO$_{4}$? A) -2. B) +5. C) 0. D) +1. Show Answer Correct Answer: B) +5. 15. Answer with TRUE or FALSE:For every oxidation in a chemical process, there must be an associated reduction. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 16. Which of these results in the formation of a precipitate? A) BaNO$_{3}$(aq) + CaCl$_{2}$(aq)$\rightarrow$. B) NaNO$_{3}$(aq) + KOH(aq)$\rightarrow$. C) More than one of these form precipitates. D) AgNO$_{3}$(aq) + NaOH(aq)$\rightarrow$. Show Answer Correct Answer: D) AgNO$_{3}$(aq) + NaOH(aq)$\rightarrow$. 17. Which of the following represents reduction? A) C $\rightarrow$ CO. B) N$_{2}$ $\rightarrow$ NH$_{3}$. C) Zn $\rightarrow$ Zn$^{2+}$. D) H$_{2}$ $\rightarrow$ H$_{2}$O. Show Answer Correct Answer: B) N$_{2}$ $\rightarrow$ NH$_{3}$. 18. In the reaction @@ext{2Fe} ..... 2ext{O} ..... 3 + 3ext{C} ightarrow 4ext{Fe} + 3ext{CO} ..... 2@@, which element is reduced? A) Iron (Fe). B) Carbon (C). C) Oxygen (O). D) None. Show Answer Correct Answer: A) Iron (Fe). 19. What is the oxidation number of hydrogen in most compounds? A) +1. B) 0. C) -1. D) +2. Show Answer Correct Answer: A) +1. 20. What is the oxidation number of chromium in Cr$_{2}$O$_{7}$$^{2-ion?}$ A) +12. B) +6. C) +7. D) +14. E) +3. Show Answer Correct Answer: B) +6. 21. Which element is getting reduced?2Mg+O$_{2}$ ..... 2MgO A) Mg. B) O. C) Both. D) None. Show Answer Correct Answer: B) O. 22. Balance the following redox reaction in acidic solution:$MnO_4^-+ Fe^{2+} \rightarrow Mn^{2+} + Fe^{3+}$ A) $MnO_4^-+ 4Fe^{2+} + 8H^+ \rightarrow Mn^{2+} + 4Fe^{3+} + 4H_2O$. B) $MnO_4^-+ 3Fe^{2+} + 4H^+ \rightarrow Mn^{2+} + 3Fe^{3+} + 2H_2O$. C) $MnO_4^-+ 2Fe^{2+} + 4H^+ \rightarrow Mn^{2+} + 2Fe^{3+} + 2H_2O$. D) $MnO_4^-+ 5Fe^{2+} + 8H^+ \rightarrow Mn^{2+} + 5Fe^{3+} + 4H_2O$. Show Answer Correct Answer: D) $MnO_4^-+ 5Fe^{2+} + 8H^+ \rightarrow Mn^{2+} + 5Fe^{3+} + 4H_2O$. 23. Which one of the following conversions is an example of reduction? A) Copper (II) oxide to copper. B) Hydrochloric acid to chlorine. C) Lead (II) nitrate to lead (II) chloride. D) Copper (II) oxide to copper (II) sulfate. Show Answer Correct Answer: A) Copper (II) oxide to copper. 24. When a gas changes iron (III) oxide to iron (II) oxide, it shows that the gas is A) A diffusible gas. B) A combustible gas. C) An oxidizing agent. D) A reducing agent. Show Answer Correct Answer: D) A reducing agent. 25. The oxidation number of S atom in S$_{2}$O$_{4}$$^{-2}$ is ..... A) +2. B) +3. C) +6. D) +4. Show Answer Correct Answer: B) +3. 26. Which of the following is a correct half-reaction for the reduction of $Cu^{2+}$ $Cu$ A) $Cu + 2e^-\rightarrow Cu^{2+}$. B) $Cu^{2+} + 2e^-\rightarrow Cu$. C) $Cu^{2+} \rightarrow Cu + 2e^-$. D) $Cu \rightarrow Cu^{2+} + 2e^-$. Show Answer Correct Answer: B) $Cu^{2+} + 2e^-\rightarrow Cu$. 27. What happens to Cr$^{3+}$ ion when it is converted to CrO$_{4}$$^{2-}$ A) Oxidation number decreases and it undergoes reduction. B) Oxidation number decreases and it undergoes oxidation. C) Oxidation number increases and it undergoes reduction. D) Oxidation number increases and it undergoes oxidation. Show Answer Correct Answer: D) Oxidation number increases and it undergoes oxidation. 28. The reducing agent is: A) Remains unchanged. B) Oxidized. C) Reduced. D) None of the above. Show Answer Correct Answer: B) Oxidized. 29. How do you determine the oxidation state of an element in a compound? A) By using a set of rules, including the known oxidation states of other elements in the compound. B) By calculating the total charge of the compound and dividing by the number of elements. C) By identifying the element's position in the periodic table and its group number. D) By assuming all elements have a zero oxidation state unless otherwise specified. Show Answer Correct Answer: A) By using a set of rules, including the known oxidation states of other elements in the compound. 30. In a redox reaction, the substance that gains electrons is called the: A) Catalyst. B) Inhibitor. C) Reductant. D) Oxidant. Show Answer Correct Answer: C) Reductant. 31. In which one of the following pairs of substances does the named element have the same oxidation state? A) Chlorine in Cl$_{2}$, and HCl. B) Iron in FeCl$_{2}$ and FeCl$_{3}$. C) Manganese in MnO$_{2}$ and MnCl$_{2}$. D) Sulfur in SO$_{3}$ and Na$_{2}$SO$_{4}$. Show Answer Correct Answer: D) Sulfur in SO$_{3}$ and Na$_{2}$SO$_{4}$. 32. What is the species that gain electrons in a redox reaction? A) Oxidizing agent. B) Is oxidized. C) Increases in oxidation number. D) Reducing agent. Show Answer Correct Answer: A) Oxidizing agent. 33. Oxidation state of chlorine increases from-1 to 0. Hence HCl is ..... agent? A) Complex. B) Oxidizing. C) Reducing. D) Redox. Show Answer Correct Answer: C) Reducing. 34. How do you determine the oxidation number of an element in a compound? A) Assign oxidation numbers based on a set of rules, including the known oxidation states of common elements and the overall charge of the compound. B) Use the periodic table to find the atomic number of the element. C) Calculate the mass of the element in the compound and divide by the total mass. D) Determine the color change of the compound when it reacts with an acid. Show Answer Correct Answer: A) Assign oxidation numbers based on a set of rules, including the known oxidation states of common elements and the overall charge of the compound. 35. What is the significance of balancing redox reactions? A) It helps to increase the reaction rate. B) It ensures that the number of atoms and the charge are conserved in the reaction. C) It allows for the formation of new products. D) It simplifies the reaction mechanism. Show Answer Correct Answer: B) It ensures that the number of atoms and the charge are conserved in the reaction. 36. Total oxidation number of a compound is equal to ..... A) Number of electrons given. B) Number of atoms. C) Zero. D) The charge of the high electronegative atom. Show Answer Correct Answer: C) Zero. 37. What is the reducing agent of this reaction?(The reactant that is oxidized.)2Al$_{(s)}$ + 6H$^{+}$$_{(aq) }$$\rightarrow$ 2Al$^{3+}$$_{ (aq)}$ + 3H$_{2(g)}$ A) Al. B) Al$^{3+}$. C) H$^{+}$. D) H$_{2}$. Show Answer Correct Answer: A) Al. 38. Identify the oxidation state of nitrogen in NH3. A) +3. B) +1. C) -3. D) -1. Show Answer Correct Answer: C) -3. 39. What substance is oxidized in the reaction, Cr+ Sn4+ $\rightarrow$ A) Cr+. B) Sn4+. C) All the above. D) None of the above. Show Answer Correct Answer: A) Cr+. 40. The purpose of a salt bridge in an electrochemical cell is to ..... A) Transfer electrons. B) Transfer water. C) Transfer protons. D) Transfer positive and negative ions. Show Answer Correct Answer: D) Transfer positive and negative ions. 41. Zinc reacts with steam to form zinc oxide and hydrogen. Zn + H$_{2}$O $\rightarrow$ ZnO + H$_{2}$ During the reaction, which substance is oxidised? A) Hydrogen. B) Zinc oxide. C) Water. D) Zinc. Show Answer Correct Answer: D) Zinc. 42. What are spectator ions? A) Ions that participate in the reaction. B) Ions that are only present in displacement reactions. C) Ions that change charge during the reaction. D) Ions that do not take part in the reaction. Show Answer Correct Answer: D) Ions that do not take part in the reaction. 43. Which substance is reduced in the reaction, Cr+ + Sn4+ $\rightarrow$ A) Cr+. B) Sn4+. C) All the above. D) None of the above. Show Answer Correct Answer: B) Sn4+. 44. The surface of copper powder becomes black due to A) Copper sulphate. B) Copper oxide. C) Copper nitrate. D) Copper carbonate. Show Answer Correct Answer: B) Copper oxide. 45. What is the main chemical reaction occurring in a hydrogen-oxygen fuel cell? A) $CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$. B) $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$. C) $2H_2 + O_2 \rightarrow 2H_2O$. D) $2Na + Cl_2 \rightarrow 2NaCl$. Show Answer Correct Answer: C) $2H_2 + O_2 \rightarrow 2H_2O$. 46. In a net ionic equation, this compound, HNO$_{2}$ A) Will stay together. B) Will break apart. C) All the above. D) None of the above. Show Answer Correct Answer: A) Will stay together. 47. In which choice is N oxidized?A. NO$_{2}$ $\rightarrow$ N$_{2}$O$_{4}$B. NO$_{3}$$^{-}$ $\rightarrow$ NO$_{2}$C. N$_{2}$O$_{5}$ $\rightarrow$ NO$_{3}$$^{-}$D. H$_{3}$N $\rightarrow$ N$_{2}$ A) A. B) C. C) B. D) D. Show Answer Correct Answer: D) D. 48. What does the mnemonic OIL RIG stand for? A) Oxygen is lost, reduction is gained. B) Oxidation is gained, reduction is lost. C) Oxidation is loss, reduction is gain. D) Oxygen is gained, reduction is lost. Show Answer Correct Answer: C) Oxidation is loss, reduction is gain. 49. Would you use an oxidizing or reducing agent for this reaction to occur?SO $4$ $2-$ $\rightarrow$ $2-$ A) Oxidizing agent. B) Reducing agent. C) All the above. D) None of the above. Show Answer Correct Answer: B) Reducing agent. 50. In which substance does sulfur have a negative oxidation number? A) CaSO$_{4}$. B) Na$_{2}$S. C) SO$_{2}$. D) S. Show Answer Correct Answer: B) Na$_{2}$S. 51. What is the oxidation of C in CH$_{4}$? A) -1. B) -4. C) +4. D) +1. Show Answer Correct Answer: B) -4. 52. In a voltaic cell, where do the electrons flow? A) From the salt bridge towards the anode. B) From the cathode to the anode. C) From the salt bridge towards the cathode. D) From the anode to the cathode. Show Answer Correct Answer: D) From the anode to the cathode. 53. In the reaction, Zn + H$_{2}$O $\rightarrow$ ZnO$_{2}$ + H$_{2, }$which element, if any, is oxidized? A) Zinc. B) Hydrogen. C) Oxygen. D) None. Show Answer Correct Answer: A) Zinc. 54. Oxygen shows positive oxidation state with which of the following element A) F. B) Na. C) Never. D) Cl. Show Answer Correct Answer: A) F. 55. This occurs when an atom's oxidation state decreases during a reaction. A) Oxidation. B) Reduction. C) Reduction-oxidation reaction. D) None of the given choices. Show Answer Correct Answer: B) Reduction. 56. A + Heat $\rightarrow$ C + D A) Endothermic. B) Exothermic. C) All the above. D) None of the above. Show Answer Correct Answer: A) Endothermic. 57. The following statements are correct in terms with the oxidation-reduction (redox) reaction, except for? A) Spontaneous redox reactions are generally endothermic. B) All redox reactions involve the transfer of electrons from one atom to another. C) Reduction can be removal of oxygen/electronegative element from a substance. D) Oxidation can be removal of hydrogen/ electropositive element from a substance. Show Answer Correct Answer: A) Spontaneous redox reactions are generally endothermic. 58. In a redox reaction, electrons are A) Transferred from the species that's reduced to the species that's oxidized. B) Transferred from the species that's oxidized to the species that's reduced. C) All the above. D) None of the above. Show Answer Correct Answer: B) Transferred from the species that's oxidized to the species that's reduced. 59. The substance that gets oxidised in a reaction is called oxidising agent. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: B) False. 60. If an atom loses electrons during a chemical reaction, the atom was: A) Oxidized. B) Neutralized. C) Reduced. D) Precipitated. Show Answer Correct Answer: A) Oxidized. ← PreviousNext →Related QuizzesScience QuizzesClass 11 QuizzesClass 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 1Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 2Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 3Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 4Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 5Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 7Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 8Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 9 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books