Oxidation-Reduction - Questions

The Oxidation-Reduction Concept Builder is comprised of 57 questions organized into 15 Question Groups and spread across three activities. The tasks required by the questions vary per activity.

Here is the breakdown of the activities:

• Two Truths and One Lie: Question Groups 1-3 ... Students are given three statements about oxidation-reduction reactions. One of the statements is false. They must identify the false statement. 
• Redox Analysis 1: Question Groups 4-9 ... Students are given the balanced chemical equation for an oxidation-reduction reaction (a synthesis reaction). They must assign appropriate oxidation numbers to each element on the reactant and product side. Then they must identify the element that is oxidized and the element that is reduced.
• Redox Analysis 2: Question Groups 10-15 ... Students are given the balanced chemical equation for an oxidation-reduction reaction. They must use oxidation numbers to identify the element that is oxidized and the element that is reduced and indicate how the oxidation state has changed (initial state and final state). Then they must identify the oxidizing agent and the reducing agent.

The questions from each group are shown below. Teachers are encouraged to view the questions in order to judge which difficulty levels are most appropriate for their classes. Alternatively, teachers can do the Concept Builder to gain a feel for the student experience. 

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Oxidation-Reduction

 
 
Activity 1: Two Truths and a Lie
Question Group 1
Question 1
Two of the following three statements are true; the other is false. Identify the false statement.

Some chemical reactions involve oxidation but not reduction; and vice versa.
An element that is oxidized is one that loses electrons.
A reducing agent is a reactant containing the element that is oxidized.

 
Question 2
Two of the following three statements are true; the other is false. Identify the false statement.
​
An element that is reduced is one that gains electrons.
In a redox reaction, reduction occurs in an early step and oxidation occurs in a later step.
An element that is oxidized experiences an increase in its oxidation number.
 

Question 3
Two of the following three statements are true; the other is false. Identify the false statement.
​
An element that is oxidized experiences an increase in its oxidation number.
A reducing agent is an electron donor.
Some chemical reactions involve oxidation but not reduction; and vice versa.
 
 

Question Group 2
Question 4
Two of the following three statements are true; the other is false. Identify the false statement.
​
An element that is oxidized experiences a decrease in its oxidation number.
It is not possible to have oxidation without also having reduction.
An element that is oxidized is one that loses electrons.
 

Question 5
Two of the following three statements are true; the other is false. Identify the false statement.
​
It is not possible to have oxidation without also having reduction.
An element that is reduced experiences an increase in its oxidation number.
An element that is oxidized is one that loses electrons.

 
Question 6
Two of the following three statements are true; the other is false. Identify the false statement.
​
An oxidizing agent is an electron acceptor.
An element that is reduced is one that gains electrons.
An element that is oxidized experiences a decrease in its oxidation number.
 

 
Question Group 3
Question 7
Two of the following three statements are true; the other is false. Identify the false statement.
​
A substance that is oxidized is one that gains electrons.
An oxidizing agent is a reactant containing the element that is reduced.
An element that is oxidized is one that loses electrons.
 
 
Question 8
Two of the following three statements are true; the other is false. Identify the false statement.
​
An oxidizing agent is a reactant containing the element that is reduced.
A substance that is reduced is one that loses electrons.
An element that is reduced is one that gains electrons.
 

Question 9
Two of the following three statements are true; the other is false. Identify the false statement.
​
A reducing agent is a reactant containing the element that is oxidized.
An element that is oxidized is one that loses electrons.
A substance that is oxidized is one that gains electrons.
 
 
 
 
 

 
Activity 2:  Redox Analysis 1
Question Group 4
Question 10
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Na  +  F₂  →  2 NaF

 

Question 11
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Na  +  Cl₂  →  2 NaCl

 

Question 12
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Na  +  Br₂  →  2 NaBr

 

Question 13
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Na  +  I₂  →  2 NaI

 
 
 
Question Group 5
Question 14
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Li  +  F₂  →  2 LiF

 

Question 15
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Li  +  Cl₂  →  2 LiCl

 

Question 16
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 K  +  Br₂  →  2 KBr

 

Question 17
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 K  +  I₂  →  2 KI

 
 
 
Question Group 6
Question 18
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

Cu +  Cl₂  →  CuCl₂

Question 19
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Al  +  3 Br₂  →  2 AlBr₃

 

Question 20
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Al  +  3 Cl₂  →  2 AlCl₃

 

Question 21
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Fe  +  3 Cl₂  →  2 FeCl₃

 
 
 

Question Group 7
Question 22
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

4 Na  +  O₂  →  2 Na₂O

Question 23
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

4 K  +  O₂  →  2 K₂O

 

Question 24
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Mg  +  O₂  →  2 MgO

 

Question 25
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Ca  +  O₂  →  2 CaO

 
 
 
Question Group 8
Question 26
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Zn  +  O₂  →  2 ZnO

 

Question 27
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

4 Ag  +  O₂  →  2 Ag₂O

 

Question 28
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

4 Fe  +  3 O₂  →  2 Fe₂O₃

 

Question 29
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

2 Cu₂O  +  O₂  →  4 CuO

 
 

Question Group 9
Question 30
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

6 Na  +  N₂  →  2 Na₃N

 

Question 31
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

6 Na  +  N₂  →  2 Na₃N

 

Question 32
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

3 Zn  +  N₂  →  Zn₃N₂

 

Question 33
Identify the oxidation states of all elements in the reactants and products. Then identify the elements that are oxidized and reduced.

6 Mg  +  P₄  →  2 Mg₃P₂

 
 
 

 
Activity 3:  Redox Analysis 2
Question Group 10
Question 34
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Ca  +  H₂  →  CaH₂

 

Question 35
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

O₂  +  2 F₂  →  2 OF₂

 

Question 36
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

4 B  +  3 O₂  →  2 B₂O₃

 
Question 37
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

N₂  +  3 H₂  →  2 NH₃

 
 
 
Question Group11
Question 38
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Cu  +  2 AgNO₃  →  Cu(NO₃)₂  +  2 Ag

 

Question 39
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

CuSO₄  +  Mg  →  MgSO₄  +  Cu

 

Question 40
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

CuSO₄  +  Fe  →  FeSO₄  +  Cu

 

Question 41
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Cu  +  H₂SO₄  →  CuSO₄  +  H₂

 
 
 
Question Group 12
Question 42
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Cl₂  +  2 NaBr  →  2 NaCl  +  Br₂

 

Question 43
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Zn  +  PbCl₂  →  ZnCl₂  +  Pb

 

Question 44
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 Al  +  6 HCl  →  2 AlCl₃  +  3 H₂

 

Question 45
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Zn  +  2 HCl  →  ZnCl₂  +  H₂

 
 

 
Question Group 13
Question 46
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Ca  +  2 H₂O  →  Ca(OH)₂  +  H₂

 
Question 47
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 Na  +  H₂O  →  2 NaOH  +  H₂

 

Question 48
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

Mg  +  2 H₂O  →  Mg(OH)₂  +  H₂

 
Question 49
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 CO₂  +  2 H₂O  →  C₂H₄  +  3 O₂

 
 
 
Question Group 14
Question 50-
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 PbS  +  3 O₂  →  2 PbO  +  2 SO₂

 


Question 51
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents. 

Fe₂O₃  +  3 CO  →  2 Fe  +  3 CO₂

 

Question 52
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 Fe₂O₃  +  3 C  →  3 CO₂  +  4 Fe

 
Question 53
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

CO₂  +  H₂  →  CO  +  H₂O

 
 
 
 
Question Group 15
Question 54
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

MnO₂  +  4 HCl  →  Cl₂  +  2 H₂O  +  MnCl₂

 

Question 55
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

2 FeCl₃  +  2 KI  →  2 FeCl₂  +  2 KCl  +  I₂

 

Question 56
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

 2 CuCl₂  +  4 KI  →  2 CuI  +  4 KCl  +  I₂

 

Question 57
Use oxidation states to determine which elements are being oxidized and reduced. Then identify the oxidizing and reducing agents.

3 CuS  +  8 HNO₃  →  3 CuSO₄  +  8 NO  + 4 H₂O