Oxidation States - Questions

The Oxidation States Concept Builder is comprised of 60 questions organized into 16 Question Groups and spread across three difficulty levels. Each question requires the same task - determining the oxidation state of one or more elements in a substance.

Here is the breakdown of the difficulty levels:

• Apprentice Difficulty Level: Question Groups 1-6 ... Students are given the formula of a simple species (e.g., element, monatomic ion, binary ionic compound, etc.) and must determine the oxidation state of the elements in the atom, ion, or compound.
• Master Difficulty Level: Question Groups 7-12 ... Students are given the formula of a compound or a polyatomic ion and must determine the oxidation state of the elements in the compound or ion.
• Wizard Difficulty Level: Question Groups 13-16 ... Students are given the formulas of three species that have one element other than oxygen or fluorine in common (e.e., nitrogen, sulfur, chlorine, or carbon) and must determine the oxidation state of that element in each of the species. 

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 States

 
Apprentice Difficulty Level
Question Group 1
Question 1
Determine the oxidation state of oxygen in the O₂ molecule. 
 
Question 2
Determine the oxidation state of nitrogen in the N₂ molecule. 
 
Question 3
Determine the oxidation state of hydrogen in the H₂ molecule. 
 
Question 4
Determine the oxidation state of chlorine in the Cl₂ molecule. 
 
 
 
Question Group 2
Question 5
Determine the oxidation state of sodium in monatomic Na. 
 
Question 6
Determine the oxidation state of iron in monatomic Fe. 
 
Question 7
Determine the oxidation state of copper in monatomic Cu. 
 
Question 8
Determine the oxidation state of zinc in monatomic Zn. 
 
 
 
Question Group 3
Question 9
Determine the oxidation state of sodium in the sodium ion, Na⁺. 
 
Question 10
Determine the oxidation state of calcium in the calcium ion, Ca²⁺. 
 
Question 11
Determine the oxidation state of aluminum in the aluminum ion, Al³⁺. 
 
Question 12
Determine the oxidation state of iron in the iron(III) ion, Fe³⁺. 
 
 
 
Question Group 4
Question 13
Determine the oxidation state of oxygen in the oxide ion, O^2-. 
 
Question 14
Determine the oxidation state of phosphorus in the phosphide ion, P^3-
 
Question 15
Determine the oxidation state of nitrogen in the nitride ion, N^3-
 
Question 16
Determine the oxidation state of sulfur in the sulfide ion, S^2-. 
 
 
 
Question Group 5
Question 17
Determine the oxidation states of the two elements – calcium and chlorine - in the compound CaCl₂.
 
Question 18
Determine the oxidation states of the two elements – magnesium and chlorine - in the compound MgCl₂.
 
Question 19
Determine the oxidation states of the two elements – magnesium and fluorine - in the compound MgF₂.
 
Question 20
Determine the oxidation states of the two elements – barium and chlorine - in the compound BaCl₂.
 
 
 
Question Group 6
Question 21
Determine the oxidation states of the two elements – sodium and oxygen - in the compound Na₂O.
 
Question 22
Determine the oxidation states of the two elements – potassium and oxygen - in the compound K₂O.
 
Question 23
Determine the oxidation states of the two elements – lithium and oxygen - in the compound Li₂O.
 
Question 24
Determine the oxidation states of the two elements – sodium and sulfur - in the compound Na₂S.
 
 
 
 
 
Master Difficulty Level
Question Group 7
Question 25
Determine the oxidation states of the two elements – nitrogen and oxygen - in the compound NO₂.
 
Question 26
Determine the oxidation states of the two elements – carbon and oxygen - in the compound CO. 
 
Question 27
Determine the oxidation states of the two elements – sulfur and oxygen - in the compound SO₂.
 
Question 28
Determine the oxidation states of the two elements – sulfur and oxygen - in the compound SO₃. 
 
 
 
Question Group 8
Question 29
Determine the oxidation states of the two elements – nitrogen and oxygen - in the compound N₂O₄.
 
Question 30
Determine the oxidation states of the two elements – nitrogen and oxygen - in the compound N₂O₅.
 
Question 31
Determine the oxidation states of the two elements – phosphorus and oxygen - in the compound P₂O₅.
 
Question 32
Determine the oxidation states of the two elements – phosphorus and oxygen - in the compound P₄O₁₀.
 
 
 
Question Group 9
Question 33
Determine the oxidation states of the two elements – phosphorus and fluorine - in the compound PF₃.
 
Question 34
Determine the oxidation states of the two elements – carbon and fluorine - in the compound CF₄.
 
Question 35
Determine the oxidation states of the two elements – sulfur and fluorine - in the compound SF₄.
 
Question 36
Determine the oxidation states of the two elements – sulfur and fluorine - in the compound SF₆.
 
 
 
Question Group 10
Question 37
Determine the oxidation states of the two elements – nitrogen and oxygen - in the polyatomic ion NO₂^-.
 
Question 38
Determine the oxidation states of the two elements – nitrogen and oxygen - in the polyatomic ion NO₃^-.
 
Question 39
Determine the oxidation states of the two elements – carbon and oxygen - in the polyatomic ion CO₃^2-.
 
Question 40
Determine the oxidation states of the two elements – carbon and oxygen - in the polyatomic ion C₂O₄^2-.
 
 
 
Question Group 11
Question 41
Determine the oxidation states of the two elements – chlorine and oxygen - in the polyatomic ion ClO₄^-.
 
Question 42
Determine the oxidation states of the two elements – chlorine and oxygen - in the polyatomic ion ClO₃^-.
 
Question 43
Determine the oxidation states of the two elements – bromine and oxygen - in the polyatomic ion BrO₄^-.
 
Question 44
Determine the oxidation states of the two elements – bromine and oxygen - in the polyatomic ion BrO₃^-.
 
 
 
Question Group 12
Question 45
Determine the oxidation states of the two elements – sulfur and oxygen - in the polyatomic ion SO₄^2-.
 
Question 46
Determine the oxidation states of the two elements – sulfur and oxygen - in the polyatomic ion SO₃^2-.
 
Question 47
Determine the oxidation states of the two elements – phosphorus and oxygen - in the polyatomic ion PO₄^3-.
 
Question 48
Determine the oxidation states of the two elements – phosphorus and oxygen - in the polyatomic ion PO₃^3-.
 
 
 
 
Wizard Difficulty Level
Question Group 13
Question 49
Identify the oxidation state of nitrogen in the following three substances:
N₂, NO₂, and Al(NO₃)₃.
 
Question 50
Identify the oxidation state of nitrogen in the following three substances:
Na₃N, NO, and NaNO₃.
 
Question 51
Identify the oxidation state of nitrogen in the following three substances:
Ca₃N₂, NO₂, and HNO₂.
 
 
 
Question Group 14
Question 52
Identify the oxidation state of sulfur in the following three substances:
Na₂S, SO₂, H₂SO₄
 
Question 53
Identify the oxidation state of sulfur in the following three substances:
H₂S, SO₃, Na₂SO₄
 
Question 54
Identify the oxidation state of sulfur in the following three substances:
K₂S, H₂SO_3, H₂SO₄
 
 
Question Group 15
Question 55
Identify the oxidation state of carbon in the following three substances:
CO, H₂C₂O₄, Na₂CO₃
 
Question 56
Identify the oxidation state of carbon in the following three substances:
CO₂, Na₂C₂O₄, H₂CO₃
 
Question 57
Identify the oxidation state of carbon in the following three substances:
CO, K₂C₂O₄, H₂CO₃
 
 
 
 
Question Group 16
Question 58
Identify the oxidation state of chlorine in the following three substances:
Cl₂, AlCl₃, HClO₃
 
Question 59
Identify the oxidation state of chlorine in the following three substances:
Cl₂, BaCl₂, HClO₄
 
 
Question 60
Identify the oxidation state of chlorine in the following three substances:
Cl₂, NaCl, HClO₂