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 1 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 11 Chemistry (Part Ii) Chapter 8 Redox Reactions Quiz 1 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. Provide an example of a redox reaction that occurs in batteries. A) Zn + 2MnO2 $\rightarrow$ ZnO + Mn2O3. B) Fe + CuSO4 $\rightarrow$ FeSO4 + Cu. C) 2H2 + O2 $\rightarrow$ 2H2O. D) C + O2 $\rightarrow$ CO2. Show Answer Correct Answer: A) Zn + 2MnO2 $\rightarrow$ ZnO + Mn2O3. 2. Haematite is reduced to iron in the blast furnace. haematite + carbon monoxide $\rightarrow$ iron +X What is X? A) Oxygen. B) Carbon. C) Hydrogen. D) Carbon dioxide. Show Answer Correct Answer: D) Carbon dioxide. 3. The oxidation number of Fe in [Fe(CN)$_{6}$]$^{-3}$ ion is A) +3. B) -3. C) +2. D) -2. Show Answer Correct Answer: A) +3. 4. What is the role of electrons in chemical bonding? A) They are exchanged in all chemical reactions. B) They prevent atoms from bonding with each other. C) They enable atoms to bond with each other to form molecules. D) They are only involved in covalent bonds. Show Answer Correct Answer: C) They enable atoms to bond with each other to form molecules. 5. Is K an oxidizing agent or reducing agent? A) Oxidizing agent. B) Reducing agent. C) Neither. D) Both. Show Answer Correct Answer: B) Reducing agent. 6. Indicate the oxidation number of phosphorus in each of the following compounds:H3PO2 A) +4. B) -1. C) +3. D) +1. E) +2. Show Answer Correct Answer: D) +1. 7. Which of these lists contains only soluble substances? Don't forget that the halides (family 17) will form precipitates with Ag+, Pb2+ and Hg2+. A) Sodium nitrate, potassium chloride, calcium carbonate. B) Lead nitrate, lead chloride, lead sulfate. C) Silver nitrate, barium sulfate, copper carbonate. D) Calcium nitrate, copper chloride, ammonium phosphate. Show Answer Correct Answer: D) Calcium nitrate, copper chloride, ammonium phosphate. 8. Fill in the blank:A redox reaction involves transfer of ..... from one reactant to another. A) Electrons. B) Neutrons. C) Protons. D) None of the above. Show Answer Correct Answer: A) Electrons. 9. From the list below, which step comes last when you are balancing half-equations? A) Add H2O to balance oxygen. B) Balance elements other that O and H. C) Balance the charge with e-. D) Add H+ to balance hydrogen. Show Answer Correct Answer: C) Balance the charge with e-. 10. What is the role of KMnO4 in redox titrations? A) KMnO4 is a catalyst in redox reactions. B) KMnO4 serves as an oxidizing agent in redox titrations. C) KMnO4 acts as a reducing agent in redox titrations. D) KMnO4 is used to measure pH levels in solutions. Show Answer Correct Answer: B) KMnO4 serves as an oxidizing agent in redox titrations. 11. In the reaction $2Mg + O_2 \rightarrow 2MgO$ A) Magnesium. B) Oxygen. C) Both Magnesium and Oxygen. D) Neither Magnesium nor Oxygen. Show Answer Correct Answer: A) Magnesium. 12. What safety precautions should be taken when conducting redox experiments in the lab? A) Wear PPE, ensure ventilation, know chemical reactivity, have neutralizing agents and spill kits, follow waste disposal procedures. B) Use open flames to heat chemicals. C) Ignore labeling on chemical containers. D) Mix all chemicals without precautions. Show Answer Correct Answer: A) Wear PPE, ensure ventilation, know chemical reactivity, have neutralizing agents and spill kits, follow waste disposal procedures. 13. Zn$_{(s)}$ $\rightarrow$ Zn$^{2+}$ $_{(aq)}$ + 2e$^{-}$ shows what type of redox reaction? A) Oxidation. B) Reduction. C) All the above. D) None of the above. Show Answer Correct Answer: A) Oxidation. 14. Substance that oxidizes another substance by accepting its electrons. A) Oxidation number. B) Oxidizing agent. C) Combustion. D) Reducing agent. Show Answer Correct Answer: B) Oxidizing agent. 15. What is reduction? A) When a chemical species lose hydrogen. B) When a chemical species gain hydrogen. C) When a chemical species lose electrons. D) When a chemical species gain electrons. Show Answer Correct Answer: D) When a chemical species gain electrons. 16. How do half-reactions help in balancing redox equations? A) They make the equations more complex. B) They eliminate the need for coefficients. C) They clarify electron transfer and ensure conservation of charge and mass. D) They simplify the equations. Show Answer Correct Answer: C) They clarify electron transfer and ensure conservation of charge and mass. 17. Which element is getting oxidised?CuSO$_{4}$+Zn$\rightarrow$Cu+ZnSO$_{4}$ A) S. B) Zn. C) O. D) Cu. Show Answer Correct Answer: B) Zn. 18. Which of the following equations is a balanced redox equation? A) $\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2$. B) $\text{C} + \text{O}_2 \rightarrow \text{CO}$. C) $\text{H}_2 + \text{O}_2 \rightarrow \text{H}_2\text{O}$. D) $\text{Na} + \text{Cl}_2 \rightarrow \text{NaCl}$. Show Answer Correct Answer: A) $\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2$. 19. Which substance is used to change iron(III) ion to iron(II) ion? A) Bromine water. B) Potassium dichromate(VI) solution. C) Potassium iodide solution. D) Acidified potassium manganate solution. Show Answer Correct Answer: C) Potassium iodide solution. 20. What is the role of a reducing agent in a redox reaction? A) It donates electrons and gets oxidized. B) It accepts electrons and gets reduced. C) It donates protons and gets oxidized. D) It accepts protons and gets reduced. Show Answer Correct Answer: A) It donates electrons and gets oxidized. 21. How do you ensure that charges are balanced in half equations? A) By adding or removing protons. B) By adding or removing neutrons. C) By changing the oxidation state. D) By adding or removing electrons. Show Answer Correct Answer: D) By adding or removing electrons. 22. What is the standard electrode potential of the hydrogen electrode? A) 0.00 V. B) 1.00 V. C) 0.34 V. D) -0.76 V. Show Answer Correct Answer: A) 0.00 V. 23. Reduction is the ..... of electrons. A) Loss. B) Transfer. C) Sharing. D) Gain. Show Answer Correct Answer: D) Gain. 24. Which of the following equations correctly represents a fuel cell operation? A) $2Na + Cl_2 \rightarrow 2NaCl$. B) $Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu$. C) $2H_2 + O_2 \rightarrow 2H_2O + energy$. D) $Cu + 2Ag^+ \rightarrow Cu^{2+} + 2Ag$. Show Answer Correct Answer: C) $2H_2 + O_2 \rightarrow 2H_2O + energy$. 25. Which of the following elements will oxidize most easily? A) Lithium. B) Chlorine. C) Aluminium. D) Hydrogen. Show Answer Correct Answer: A) Lithium. 26. Iron (II) ions, Fe$^{2+}$ in a solution can be changed to iron (III), Fe$^{3+}$ by adding solution X. What is X? A) Acidified potassium manganate (VII). B) Sodium hydroxide. C) Potassium hexacyanoferrate(II). D) Sodium thiosulphate. Show Answer Correct Answer: A) Acidified potassium manganate (VII). 27. In the reaction 2H2S + O2 $\rightarrow$ 2S + 2H2O, which species is reduced? A) H2O. B) H2S. C) S. D) O2. Show Answer Correct Answer: D) O2. 28. Which of the following is NOT a type of redox reaction? A) Displacement reactions. B) Neutralization reactions. C) Combination reactions. D) Decomposition reactions. Show Answer Correct Answer: B) Neutralization reactions. 29. Net ionic equation A) The ions in a chemical reaction that remain aqueous throughout the entire reaction. B) The chemical equation that represents the ions that are participating in the actual chemistry. The spectator ions are removed from the overall equation to reveal the net ionic equation. C) An insoluble (solid) substance that is formed from two soluble (aqueous) substances. D) Both matter and mass are conserved throughout a chemical reaction. Show Answer Correct Answer: B) The chemical equation that represents the ions that are participating in the actual chemistry. The spectator ions are removed from the overall equation to reveal the net ionic equation. 30. What happens during the corrosion of iron? A) Iron loses oxygen. B) Iron loses electrons. C) Iron gains oxygen. D) Iron gains electrons. Show Answer Correct Answer: C) Iron gains oxygen. 31. What is the meaning of reduction? A) Gain of electron. B) Gain of oxygen. C) Loss of electron. D) Loss of hydrogen. Show Answer Correct Answer: A) Gain of electron. 32. What is the oxidation state of H in H$_{2}$? A) +2. B) +1. C) 0. D) None of the above. Show Answer Correct Answer: C) 0. 33. WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:Balance the following reactions using changing oxidation number method.MnO$_{4}$$^{-}$(aq) + H$^{+}$(aq) + I$^{-}$ (aq) $\rightarrow$ Mn$^{2+}$(aq) + I$_{2}$(s)How many electrons water compound produced in the reaction? A) 9. B) 8. C) 10. D) 7. Show Answer Correct Answer: B) 8. 34. What does the term 'reductant' refer to? A) A substance that is reduced. B) A substance that is oxidized. C) A substance that gains electrons. D) A substance that loses electrons. Show Answer Correct Answer: D) A substance that loses electrons. 35. Which of the following reactions is a redox reaction? A) $AgNO_3 + NaCl \rightarrow AgCl + NaNO_3$. B) $NaOH + HCl \rightarrow NaCl + H_2O$. C) $H_2 + Cl_2 \rightarrow 2HCl$. D) $CaCO_3 \rightarrow CaO + CO_2$. Show Answer Correct Answer: C) $H_2 + Cl_2 \rightarrow 2HCl$. 36. How is the standard electrode potential of a half-cell measured? A) By comparing it to the potential of a standard hydrogen electrode under standard conditions. B) By measuring the amount of gas produced in the reaction. C) By calculating the difference in mass of the electrode before and after the reaction. D) By observing the color change of the solution. Show Answer Correct Answer: A) By comparing it to the potential of a standard hydrogen electrode under standard conditions. 37. Assertion:Sulphur dioxide and chlorine are oth bleaching agents.Reason:Both are reducing agents. A) Both assertion and reason are true and the reason is the correct explanation of asserton. B) Both assertion and reason are true but the reason is not the correct explanation of asserton. C) Assertion is true and the reason is false. D) Both assertion and reason are false. Show Answer Correct Answer: C) Assertion is true and the reason is false. 38. It contains the element that is reduced. A) Reactant. B) Reductant. C) Oxidant. D) Reagent. Show Answer Correct Answer: C) Oxidant. 39. What is the balanced equation for the reaction of hydrogen peroxide (H2O2) with iodide ions (I-) in basic solution? A) H2O2 + 2 I-$\rightarrow$ I2 + 2 OH-. B) H2O2 + I-$\rightarrow$ I2 + H2O. C) 2 H2O2 + I-$\rightarrow$ I2 + 2 H2O. D) 2 H2O2 + 2 I-$\rightarrow$ I2 + 2 H2O + 2 OH-. Show Answer Correct Answer: D) 2 H2O2 + 2 I-$\rightarrow$ I2 + 2 H2O + 2 OH-. 40. An increase in oxidation number. A) OIL RIG. B) Reduction. C) Oxdiation. D) Redox. Show Answer Correct Answer: C) Oxdiation. 41. In the reaction $\text{2Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}$ A) Sodium (Na). B) Chlorine (Cl). C) Sodium chloride (NaCl). D) None. Show Answer Correct Answer: B) Chlorine (Cl). 42. In redox reactions most nonmetals have tendency to ..... A) Take electrons. B) Oxidize. C) Give protons. D) Give electrons. Show Answer Correct Answer: A) Take electrons. 43. What is oxidation? A) Loss of oxygen. B) Gain of oxygen. C) All the above. D) None of the above. Show Answer Correct Answer: B) Gain of oxygen. 44. Identify the reducing agent in a redox reaction. A) The reducing agent is the substance that donates electrons. B) The reducing agent is the substance that accepts electrons. C) The reducing agent is the substance that increases oxidation state. D) The reducing agent is the substance that remains unchanged. Show Answer Correct Answer: A) The reducing agent is the substance that donates electrons. 45. Which of the following represents a redox reaction:2H2 + O2 $\rightarrow$ 2H2O or NaCl $\rightarrow$ Na + Cl2? A) 2H2 + O2 $\rightarrow$ 2H2O. B) 2Na + Cl2 $\rightarrow$ 2NaCl. C) H2 + O2 $\rightarrow$ H2O. D) 2H2 + Cl2 $\rightarrow$ 2HCl. Show Answer Correct Answer: A) 2H2 + O2 $\rightarrow$ 2H2O. 46. What is the precipitate formed between potassium bromide and ammonium sulfide A) No ppt is formed. B) Potassium ammonium. C) Ammonium bromide. D) Potassium sulfide. Show Answer Correct Answer: A) No ppt is formed. 47. A decrease in oxidation number. A) Redox. B) Reduction. C) Oxidation. D) Dilute. Show Answer Correct Answer: B) Reduction. 48. Which of the following reactions is balanced by both mass and charge? A) Fe$^{+2}$ + Al $\rightarrow$Fe + Al$^{+3}$. B) Cu + Fe$^{+2}$ $\rightarrow$ Cu$^{+1}$ + Fe$^{+3}$. C) Fe$^{+2}$ + 2 Cu $\rightarrow$ 2 Cu$^{+}$ + Fe. D) F$_{2}$ + Br$^{-}$ $\rightarrow$ F$^{-}$ + Br$_{2}$. Show Answer Correct Answer: C) Fe$^{+2}$ + 2 Cu $\rightarrow$ 2 Cu$^{+}$ + Fe. 49. Which half-reaction correctly represents reduction? A) F$_{2}$ $\rightarrow$ 2 F$^{-}$+ 2e$^{-}$. B) Ag $\rightarrow$ Ag$^{+}$ + e$^{-}$. C) Fe$^{2+}$+ e$^{-}$ $\rightarrow$ Fe$^{3+}$. D) Au$^{3+}$ + 3e$^{-}$$\rightarrow$ Au. Show Answer Correct Answer: D) Au$^{3+}$ + 3e$^{-}$$\rightarrow$ Au. 50. How does a block of zinc attached to a steel ship hull protect the hull from corrosion? A) The zinc carries electrons toward the iron so that the iron cannot react. B) Zinc is a better reducing agent so it corrodes instead of the iron corroding. C) Zinc is a better oxidising agent so it corrodes instead of the iron corroding. D) The zinc carries electrons away from the iron so that the iron cannot react. Show Answer Correct Answer: B) Zinc is a better reducing agent so it corrodes instead of the iron corroding. 51. If in a reaction, copper is reduced; its number of electrons has: A) Increased. B) Decreased. C) Remained constant. D) Varied randomly. Show Answer Correct Answer: A) Increased. 52. In a redox reaction, what is the role of the oxidizing agent? A) The oxidizing agent donates electrons and is oxidized in the process. B) The oxidizing agent accepts electrons and is reduced in the process. C) The oxidizing agent remains unchanged throughout the reaction. D) The oxidizing agent increases the temperature of the reaction. Show Answer Correct Answer: B) The oxidizing agent accepts electrons and is reduced in the process. 53. Which of the following best describes a redox reaction? A) A chemical reaction where electrons are transferred. B) A chemical reaction where electrons are lost. C) A chemical reaction where electrons are gained. D) None of the above. Show Answer Correct Answer: A) A chemical reaction where electrons are transferred. 54. How can you identify a redox reaction? A) Look for changes in oxidation states of elements in the reactants and products. B) Identify the presence of catalysts in the reaction. C) Check if the reaction involves a gas release. D) Observe the temperature change during the reaction. Show Answer Correct Answer: A) Look for changes in oxidation states of elements in the reactants and products. 55. What is a correct half reaction for the following reaction:2 Al + N$_{2 }$$\rightarrow$ 2 AlN A) N$^{0}$ $\rightarrow$ N$^{+2}$ + 2 e$^{-1}$. B) Al$^{0}$ + 3 e$^{-}$ $\rightarrow$ Al$^{+3}$. C) N$^{0}$ + 3 e$^{-1}$ $\rightarrow$ N$^{-3}$. D) Al$^{+3}$ + 3 e$^{-1}$ $\rightarrow$ Al$^{0}$. Show Answer Correct Answer: C) N$^{0}$ + 3 e$^{-1}$ $\rightarrow$ N$^{-3}$. 56. What is the oxidation state of carbon in CO2? A) -4. B) 0. C) +4. D) +2. Show Answer Correct Answer: C) +4. 57. Which reducing agent is used in the production of iron in a blast furnace? A) Calcium carbonate (limestone). B) Carbon dioxide. C) Carbon. D) Carbon monoxide. Show Answer Correct Answer: D) Carbon monoxide. 58. During an oxidation-reduction reaction, the number of electrons gained is A) Equal to the number of protons gained. B) Less than the number of electrons lost. C) Less than the number of protons gained. D) Equal to the number of electrons lost. Show Answer Correct Answer: D) Equal to the number of electrons lost. 59. WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:Balance the following ACIDIC reactions using the half-reaction method.MnO$_{4}$$^{-}$(aq) + H$^{+}$(aq) + I$^{-}$ (aq) $\rightarrow$ Mn$^{2+}$(aq) + I$_{2}$(s)Water is a product of this reaction. What is the coefficient of water in the final balanced equation? A) 16. B) 5. C) 8. D) 2. Show Answer Correct Answer: C) 8. 60. What is a correct half-reaction of this equation, Cu$^{+}$+ Fe $\rightarrow$ Fe$^{3+}$+ Cu? A) 3Cu$^{+}$ + 3e$^{-}$$\rightarrow$ 3Cu. B) Cu$^{+}$ $\rightarrow$ Cu. C) Fe + 3e$^{-}$$\rightarrow$ Fe$^{3+}$. D) Fe $\rightarrow$ Fe$^{3+}$. Show Answer Correct Answer: A) 3Cu$^{+}$ + 3e$^{-}$$\rightarrow$ 3Cu. 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