1. What is the oxidation number of sulfur in sulfuric acid (H₂SO₄)?
A) +2
B) +4
C) +6
D) -2
View AnswerC
2. In electrolysis, the process of breaking down a compound using electricity is called:
A) Oxidation
B) Reduction
C) Electrolysis
D) Neutralization
View AnswerC
3. Which electrode undergoes reduction during electrolysis?
A) Anode
B) Cathode
C) Salt bridge
D) Electrolyte
View AnswerB
4. What is the standard electrode potential of the hydrogen electrode?
A) 0.00 V
B) 1.00 V
C) -0.76 V
D) +0.76 V
View AnswerA
5. The electrode potential of a half-cell is influenced by:
A) Concentration of ions
B) Temperature
C) Pressure
D) All of the above
View AnswerD
6. In balancing redox equations, the ion-electron method is used to balance:
A) Mass only
B) Charge only
C) Both mass and charge
D) Neither mass nor charge
View AnswerC
7. Which of the following represents the oxidation state of chlorine in NaCl?
A) +1
B) +2
C) -1
D) 0
View AnswerC
8. During electrolysis, the substance that is oxidized is located at the:
A) Cathode
B) Anode
C) Electrolyte
D) Salt bridge
View AnswerB
9. What is the first step in the ion-electron method of balancing redox reactions?
A) Assign oxidation states
B) Write the half-reactions
C) Balance the electrons
D) Combine the half-reactions
View AnswerA
10. In which type of cell does electrolysis occur?
A) Galvanic cell
B) Electrolytic cell
C) Concentration cell
D) Fuel cell
View AnswerB
11. The half-reaction for the reduction of copper ions is:
A) Cu²⁺ + 2e⁻ → Cu
B) Cu → Cu²⁺ + 2e⁻
C) Cu + 2e⁻ → Cu²⁺
D) Cu²⁺ + e⁻ → Cu
View AnswerA
12. What is the oxidation state of nitrogen in ammonia (NH₃)?
A) -3
B) +1
C) +3
D) +5
View AnswerA
13. In the oxidation number change method, which element’s oxidation state must be tracked?
A) Only the oxidizing agent
B) Only the reducing agent
C) All elements involved
D) None of the elements
View AnswerC
14. Which of the following is a common application of electrolysis?
A) Electroplating
B) Battery operation
C) Fuel production
D) All of the above
View AnswerD
15. What is the purpose of a salt bridge in an electrochemical cell?
A) To conduct electricity
B) To prevent mixing of solutions
C) To maintain charge balance
D) To catalyze the reaction
View AnswerC
16. Which of the following reactions represents oxidation?
A) 2H₂ + O₂ → 2H₂O
B) Cu²⁺ + 2e⁻ → Cu
C) Zn → Zn²⁺ + 2e⁻
D) 2Na + Cl₂ → 2NaCl
View AnswerC
17. The reduction half-reaction involves:
A) Gain of electrons
B) Loss of electrons
C) Gain of protons
D) Loss of protons
View AnswerA
18. In an electrolytic cell, the cathode is:
A) Positively charged
B) Negatively charged
C) Neutral
D) None of the above
View AnswerB
19. The standard reduction potential of a half-cell indicates:
A) The strength of the oxidizing agent
B) The strength of the reducing agent
C) The temperature of the system
D) The concentration of ions
View AnswerA
20. Which of the following represents a redox reaction?
A) 2H₂ + O₂ → 2H₂O
B) NaOH + HCl → NaCl + H₂O
C) CaCO₃ → CaO + CO₂
D) H₂ + Cl₂ → 2HCl
View AnswerA
21. In balancing redox reactions by the oxidation number change method, what is the first step?
A) Assign oxidation states
B) Write the half-reactions
C) Balance the electrons
D) Combine the half-reactions
View AnswerA
22. Which of the following ions has the highest oxidation state?
A) Fe²⁺
B) Cu²⁺
C) MnO₄⁻
D) CrO₄²⁻
View AnswerC
23. In an electrochemical cell, the anode is the site of:
A) Oxidation
B) Reduction
C) Neutralization
D) Catalysis
View AnswerA
24. What is the oxidation number of carbon in carbon dioxide (CO₂)?
A) +2
B) +4
C) -2
D) 0
View AnswerB
25. The standard electrode potential for a reduction half-reaction is:
A) Always positive
B) Always negative
C) Can be positive or negative
D) Equal to zero
View AnswerC
26. Which of the following correctly describes a galvanic cell?
A) Converts chemical energy to electrical energy
B) Requires an external power source
C) Involves electrolysis
D) None of the above
View AnswerA
27. During electrolysis of water, the gas produced at the anode is:
A) Oxygen
B) Hydrogen
C) Nitrogen
D) Chlorine
View AnswerA
28. The overall reaction in an electrochemical cell can be determined by:
A) Adding the oxidation and reduction half-reactions
B) Multiplying the half-reactions by coefficients
C) Balancing the charges
D) All of the above
View AnswerD
29. The term “reductant” refers to:
A) The species that gains electrons
B) The species that loses electrons
C) The species that remains unchanged
D) The species that is neutral
View AnswerB
30. In balancing redox reactions, the total charge must be:
A) Zero
B) Equal on both sides
C) Maximized
D) Unbalanced
View AnswerB
31. The oxidation state of oxygen in peroxides is:
A) -1
B) -2
C) 0
D) +2
View AnswerA
32. The process of electrolysis can be used to extract:
A) Metals from ores
B) Chlorine from brine
C) Hydrogen from water
D) All of the above
View AnswerD
33. Which of the following is true about electrode potentials?
A) They are always positive
B) They depend on the concentration of ions
C) They are independent of temperature
D) They do not affect reaction rates
View AnswerB
34. The oxidation state of iron in Fe₂O₃ is:
A) +2
B) +3
C) +4
D) +6
View AnswerB
35. In balancing redox equations, what must be done to the electrons lost in oxidation?
A) Ignore them
B) Add them to the reduction half-reaction
C) Subtract them from the reduction half-reaction
D) Convert them to protons
View AnswerB
36. The reduction potential of a half-cell indicates:
A) Its tendency to lose electrons
B) Its tendency to gain electrons
C) Its temperature dependence
D) Its pressure dependence
View AnswerB
37. What is the overall cell potential of a galvanic cell composed of a zinc and copper half-cell?
A) 0.00 V
B) 1.10 V
C) -0.76 V
D) +0.76 V
View AnswerB
38. In which type of electrochemical reaction is energy absorbed?
A) Galvanic cell
B) Electrolytic cell
C) Concentration cell
D) None of the above
View AnswerB
39. What does the term “half-cell” refer to in electrochemistry?
A) One of the two electrodes in a cell
B) The entire electrochemical cell
C) The electrolyte solution
D) The salt bridge
View AnswerA
40. Which of the following statements is correct about a salt bridge?
A) It allows the flow of electrons
B) It maintains electrical neutrality
C) It is made of metal
D) It increases the resistance of the cell
View AnswerB
41. The oxidation state of phosphorus in phosphoric acid (H₃PO₄) is:
A) +1
B) +3
C) +5
D) -3
View AnswerC
42. What is the balanced equation for the electrolysis of water?
A) 2H₂O → 2H₂ + O₂
B) 2H₂O → H₂ + O
C) H₂O → H + O₂
D) 2H₂ + O₂ → 2H₂O
View AnswerA
43. The overall reaction in a galvanic cell involves:
A) Oxidation at the anode and reduction at the cathode
B) Reduction at the anode and oxidation at the cathode
C) Both oxidation and reduction at the anode
D) No net change
View AnswerA
44. The process of balancing redox equations by the oxidation number change method involves:
A) Adjusting coefficients to equalize charges
B) Balancing the number of atoms of each element
C) Calculating the change in oxidation states
D) All of the above
View AnswerD
45. Which of the following represents a galvanic cell?
A) A cell that converts chemical energy into electrical energy
B) A cell that requires an external power source
C) A cell that involves electrolysis
D) A cell that produces heat
View AnswerA
46. The process of balancing redox equations involves determining:
A) Oxidation states
B) Electrode potentials
C) The overall cell reaction
D) All of the above
View AnswerD
47. The standard potential for a reduction reaction is given by the:
A) Nernst equation
B) Gibbs free energy equation
C) Faraday’s law
D) Hess’s law
View AnswerA
48. In a redox reaction, the species that is reduced is:
A) The oxidizing agent
B) The reducing agent
C) A spectator ion
D) None of the above
View AnswerA
49. The oxidation state of chromium in potassium dichromate (K₂Cr₂O₇) is:
A) +3
B) +6
C) +5
D) +2
View AnswerB
50. The balanced equation for the reaction of zinc with copper(II) sulfate is:
A) Zn + CuSO₄ → ZnSO₄ + Cu
B) Zn + 2CuSO₄ → ZnSO₄ + 2Cu
C) 2Zn + CuSO₄ → 2ZnSO₄ + Cu
D) Zn + Cu → ZnCu
View AnswerA
51. The oxidation state of carbon in methane (CH₄) is:
A) -4
B) +4
C) 0
D) +2
View AnswerA
52. In electrolysis, the electrolyte is:
A) The substance being reduced
B) The substance being oxidized
C) The ionic solution conducting electricity
D) The metal electrode
View AnswerC
53. Which of the following is a characteristic of a reducing agent?
A) Gains electrons
B) Loses electrons
C) Increases oxidation state
D) Both B and C
View AnswerD
54. The term “electrode” refers to:
A) A conductive material that facilitates the flow of electrons
B) The salt bridge
C) The electrolyte solution
D) The reaction vessel
View AnswerA
55. In a galvanic cell, the anode is where:
A) Electrons are gained
B) Oxidation occurs
C) Reduction occurs
D) The salt bridge is located
View AnswerB
56. The oxidation number of hydrogen in water (H₂O) is:
A) +1
B) -1
C) 0
D) +2
View AnswerA
57. In balancing redox equations, what does “oxidation” refer to?
A) Gain of electrons
B) Loss of electrons
C) Change in temperature
D) Change in pressure
View AnswerB
58. The process of electrolysis can be used to:
A) Separate chemical compounds
B) Produce chlorine gas
C) Plate metals
D) All of the above
View AnswerD
59. The oxidation state of chlorine in ClO₃⁻ is:
A) -1
B) +1
C) +5
D) +7
View AnswerC
60. Which of the following species is oxidized in the reaction 2Fe + 3Cu²⁺ → 2Fe²⁺ + 3Cu?
A) Fe
B) Cu²⁺
C) Fe²⁺
D) Cu
View AnswerA
61. The standard electrode potential is a measure of:
A) The energy change during a reaction
B) The driving force for a reaction
C) The total mass of reactants
D) The temperature of the system
View AnswerB
62. In balancing a redox reaction, what is the total charge on the left side of the equation 2MnO₄⁻ + 16H⁺ + 5C₂O₄²⁻ → 2Mn²⁺ + 8H₂O + 10CO₂?
A) +10
B) +8
C) -8
D) -2
View AnswerB
63. What is the balanced equation for the reduction of permanganate ion in acidic solution?
A) MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O
B) MnO₄⁻ + 4H₂O + 8e⁻ → Mn²⁺ + 8H⁺
C) MnO₄⁻ + 2e⁻ → MnO₂ + 4H⁺
D) MnO₄⁻ + e⁻ → MnO₂ + H₂O
View AnswerA
64. The oxidation state of the metal in a salt is typically:
A) Higher than the non-metal
B) Lower than the non-metal
C) Dependent on the non-metal
D) Equal to zero
View AnswerC
65. Which of the following best describes an electrolytic cell?
A) Spontaneous reaction
B) Non-spontaneous reaction driven by an external voltage
C) Produces electrical energy
D) Does not require a power source
View AnswerB
66. The oxidation number of manganese in KMnO₄ is:
A) +2
B) +4
C) +5
D) +7
View AnswerD
67. In the half-reaction method, what is the purpose of adding H⁺ ions?
A) To balance the number of oxygen atoms
B) To balance the charges
C) To increase the temperature
D) To decrease the pH
View AnswerA
68. In a redox reaction, the species that loses electrons is:
A) The reducing agent
B) The oxidizing agent
C) A spectator ion
D) None of the above
View AnswerA
69. The oxidation state of sodium in NaCl is:
A) +1
B) -1
C) 0
D) +2
View AnswerA
70. The half-cell potential for the reaction Zn²⁺ + 2e⁻ → Zn is:
A) +0.76 V
B) -0.76 V
C) +1.10 V
D) +2.00 V
View AnswerB
71. The overall cell potential of a galvanic cell is influenced by:
A) Concentration of reactants
B) Temperature
C) Pressure
D) All of the above
View AnswerD
72. In electrolysis, the electrode where oxidation occurs is called:
A) Anode
B) Cathode
C) Salt bridge
D) Electrode
View AnswerA
73. What is the oxidation state of nitrogen in ammonia (NH₃)?
A) -3
B) +3
C) +5
D) 0
View AnswerA
74. The balanced equation for the reduction of silver ions (Ag⁺) to silver metal (Ag) is:
A) Ag⁺ + e⁻ → Ag
B) 2Ag⁺ + 2e⁻ → Ag₂
C) 2Ag + e⁻ → Ag²⁺
D) 2Ag⁺ + e⁻ → 2Ag
View AnswerA
75. The change in oxidation number indicates:
A) A chemical reaction occurred
B) No reaction occurred
C) A physical change
D) An equilibrium state
View AnswerA
76. The electrode potential of a half-cell is influenced by:
A) Concentration of ions
B) Temperature
C) Pressure
D) All of the above
View AnswerD
77. The balanced equation for the oxidation of iron(II) to iron(III) is:
A) Fe²⁺ → Fe³⁺ + e⁻
B) Fe → Fe³⁺ + 3e⁻
C) Fe²⁺ + 2e⁻ → Fe
D) 2Fe²⁺ + 2e⁻ → 2Fe³⁺
View AnswerA
78. In the Nernst equation, the term RT/nF accounts for:
A) Temperature and number of moles
B) Charge and Faraday’s constant
C) Concentration of reactants
D) Reaction time
View AnswerA
79. The half-cell potential of a reaction is determined by:
A) Standard reduction potential
B) Electrode area
C) Temperature
D) All of the above
View AnswerA
80. The oxidation state of sulfur in H₂SO₄ is:
A) +2
B) +4
C) +6
D) +8
View AnswerC
81. In balancing redox reactions, the “ion-electron method” is also known as:
A) Half-reaction method
B) Full reaction method
C) Oxidation number method
D) Charge balance method
View AnswerA
82. The oxidation state of lead in Pb(NO₃)₂ is:
A) +2
B) +4
C) +6
D) +3
View AnswerB
83. The reaction in which the oxidation state of an element decreases is called:
A) Oxidation
B) Reduction
C) Neutralization
D) Hydrolysis
View AnswerB
84. The species that is oxidized in the reaction 2H₂ + O₂ → 2H₂O is:
A) H₂
B) O₂
C) H₂O
D) None of the above
View AnswerA
85. Which of the following statements about electrode potentials is true?
A) A higher potential means a stronger oxidizing agent
B) A higher potential means a stronger reducing agent
C) Electrode potentials cannot be compared
D) All electrode potentials are positive
View AnswerA
86. The balanced equation for the oxidation of dichromate ion in acidic solution is:
A) Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O
B) Cr₂O₇²⁻ + 8H⁺ + 6e⁻ → 2Cr³⁺ + 4H₂O
C) Cr₂O₇²⁻ + 6H₂O + 6e⁻ → 2Cr³⁺ + 12H⁺
D) Cr₂O₇²⁻ + 4H₂O + 3e⁻ → 2Cr³⁺ + 8H⁺
View AnswerA
87. What is the oxidation state of oxygen in H₂O₂ (hydrogen peroxide)?
A) -1
B) 0
C) +1
D) -2
View AnswerA
88. In a redox reaction, the oxidizing agent is:
A) The species that is reduced
B) The species that is oxidized
C) The species that remains unchanged
D) None of the above
View AnswerA
89. The balanced equation for the electrolysis of sodium chloride solution (brine) produces:
A) H₂, Cl₂, NaOH
B) Na, Cl, H₂O
C) H₂, Na, Cl
D) NaCl, H₂O
View AnswerA
90. Which of the following is a method for determining the oxidation state of an element?
A) By observing the charge of the ion
B) By analyzing the molecular structure
C) Both A and B
D) None of the above
View AnswerC
91. In the reaction 2Fe + 3Cu²⁺ → 2Fe²⁺ + 3Cu, which element is being reduced?
A) Fe
B) Cu²⁺
C) Fe²⁺
D) Cu
View AnswerB
92. The oxidation state of phosphorus in phosphine (PH₃) is:
A) +1
B) +3
C) -3
D) 0
View AnswerC
93. The process of electrolysis is used in the production of:
A) Metals from ores
B) Chlorine from brine
C) Hydrogen from water
D) All of the above
View AnswerD
94. The overall reaction in an electrolytic cell is:
A) Spontaneous
B) Non-spontaneous
C) Always exothermic
D) None of the above
View AnswerB
95. The half-cell potential of a standard hydrogen electrode is defined as:
A) 0.00 V
B) 1.00 V
C) -0.76 V
D) +0.76 V
View AnswerA
96. The oxidation state of nitrogen in NO₃⁻ is:
A) +1
B) +3
C) +5
D) +7
View AnswerC
97. In the reaction H₂ + F₂ → 2HF, which species is oxidized?
A) H₂
B) F₂
C) HF
D) None of the above
View AnswerA
98. The process of balancing redox equations is necessary to ensure:
A) The conservation of mass
B) The conservation of charge
C) Both A and B
D) None of the above
View AnswerC
99. The standard electrode potential for a reduction half-reaction is always:
A) Positive
B) Negative
C) Zero
D) Depends on the conditions
View AnswerD
100. The oxidation state of zinc in ZnO is:
A) +1
B) +2
C) 0
D) -1
View AnswerB