Redox Processes Practice Questions
IB (International Baccalaureate) · IB Chemistry HL · 148 free MCQs with instant results and detailed explanations.
148
Total
47
Easy
72
Medium
29
Hard
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Sample Questions from Redox Processes
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Q1
Easy
Which of the following statements about oxidation and reduction is correct?
A.
Oxidation involves the loss of electrons.
B.
Reduction involves the gain of protons.
C.
Oxidation and reduction can occur simultaneously in different reactions.
D.
Reduction always involves the loss of oxygen.
Show Answer & Explanation
Correct Answer: A
Oxidation is defined as the loss of electrons by a substance, which increases its oxidation state. Therefore, option A is correct as it accurately describes this fundamental concept of redox processes.
Q2
Easy
In the redox reaction between zinc and copper(II) sulfate, which species is oxidized?
A.
Zinc
B.
Copper(II)
C.
Copper(I)
D.
Sulphate ion
Show Answer & Explanation
Correct Answer: A
In this reaction, zinc (Zn) loses electrons to become zinc ions (Zn²⁺), which means it undergoes oxidation. Therefore, the correct answer is A, as zinc is indeed the species being oxidized.
Q3
Easy
What is the standard reduction potential of a half-cell if the half-reaction is represented as Cu²⁺ + 2e⁻ → Cu and the E° is +0.34 V?
A.
+0.34 V
B.
-0.34 V
C.
0 V
D.
+2.34 V
Show Answer & Explanation
Correct Answer: A
The standard reduction potential given in the question (+0.34 V) indicates that the half-reaction of copper ions being reduced to copper metal is indeed +0.34 V, which is a direct reflection of the half-cell's ability to gain electrons.
Q4
Medium
In a redox reaction, which species is reduced?
A.
The species that gains electrons
B.
The species that loses electrons
C.
The species that is oxidized
D.
The species that remains unchanged
Show Answer & Explanation
Correct Answer: A
In redox reactions, reduction is defined as the gain of electrons. This means the species that undergoes reduction will acquire electrons and thus its oxidation state decreases.
Q5
Medium
What is the standard electrode potential of the half-reaction Zn^2+ + 2e^- → Zn if given the standard electrode potential for Cu^2+ + 2e^- → Cu as +0.34 V?
A.
-0.76 V
B.
+0.76 V
C.
+0.34 V
D.
-0.34 V
Show Answer & Explanation
Correct Answer: A
The standard electrode potential for Zn^2+ + 2e^- → Zn is -0.76 V, which is derived from the Nernst equation and the given potential of Cu. When coupled with Cu, Zn is a stronger reducing agent, thus it has a negative potential.
Q6
Medium
In an electrochemical cell, if the anode reaction is 2Ag^+ + Zn → 2Ag + Zn^2+, what is the overall cell reaction?
A.
Zn + 2Ag^+ → 2Ag + Zn^2+
B.
2Ag + Zn^2+ → 2Ag^+ + Zn
C.
Zn + 2Ag → Zn^2+ + 2Ag^+
D.
2Ag + Zn → 2Ag^+ + Zn^2+
Show Answer & Explanation
Correct Answer: A
The overall cell reaction is derived by writing the anode and cathode reactions. The anode reaction shows zinc being oxidized, while silver ions are reduced, giving the overall reaction: Zn + 2Ag^+ → 2Ag + Zn^2+.
Q7
Medium
Which of the following species acts as a reducing agent in the reaction 2MnO4^- + 5C2O4^2- + 16H^+ → 2Mn^2+ + 10CO2 + 8H2O?
A.
MnO4^-
B.
C2O4^2-
C.
H^+
D.
CO2
Show Answer & Explanation
Correct Answer: B
In this reaction, C2O4^2- (oxalate ion) is oxidized to CO2, indicating that it loses electrons and thus acts as the reducing agent. The MnO4^- is reduced to Mn^2+.
Q8
Hard
Which of the following statements correctly describes the change in oxidation states in the redox reaction: 2MnO4- + 16H+ + 10e- → 2Mn2+ + 8H2O?
A.
Manganese is reduced from +7 to +2.
B.
Manganese is oxidized from +2 to +7.
C.
Oxygen is reduced from -2 to 0.
D.
Hydrogen is oxidized from 0 to +1.
Show Answer & Explanation
Correct Answer: A
In this reaction, manganese in MnO4- has an oxidation state of +7 and is reduced to +2 in Mn2+. Therefore, statement A is correct as it accurately describes the reduction of manganese.
Q9
Hard
In an electrochemical cell, the standard reduction potentials are given as follows: Cu2+ + 2e- → Cu (E° = +0.34 V) and Ag+ + e- → Ag (E° = +0.80 V). Which of the following statements is true regarding the spontaneous reaction between these ions?
A.
Cu will be reduced at the cathode.
B.
Ag will be oxidized at the anode.
C.
The cell potential will be negative.
D.
Ag will be reduced at the cathode.
Show Answer & Explanation
Correct Answer: D
Since Ag has a higher standard reduction potential than Cu, Ag will be reduced at the cathode. Therefore, statement D is correct, as the spontaneous reaction will occur with Ag gaining electrons.
Q10
Hard
In a redox reaction, the standard reduction potential of a half-reaction is +0.34 V. If the concentration of the oxidizer is increased, which statement is true regarding the reaction's direction?
A.
The reaction will shift to the right, favoring the formation of products.
B.
The reaction will shift to the left, favoring the formation of reactants.
C.
The reaction will remain at equilibrium regardless of concentration changes.
D.
The reaction will proceed with increased activation energy.
Show Answer & Explanation
Correct Answer: A
According to Le Chatelier's Principle, increasing the concentration of reactants (oxidizers) shifts the equilibrium to the right, favoring product formation. This aligns with the positive standard reduction potential indicating a favorable reaction.
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Redox Processes — IB (International Baccalaureate) IB Chemistry HL Practice Questions Online
This page contains 148 practice MCQs for the chapter Redox Processes in IB (International Baccalaureate) IB Chemistry HL. The questions are organized by difficulty — 47 easy, 72 medium, 29 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.