Sub-topic 1
2025 · National Semifinal
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Electrons needed to balance the reduction half-reaction of mno4- in basic medium
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Sub-topic 2
2025 · National Semifinal
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Percentage by mass of oxygen in an oxide from a non-integer oxidation state
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Sub-topic 3
2026 · National Quarterfinal
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Sum of the oxidation states of an element across several of its compounds
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Sub-topic 4
2026 · National One-Eighth
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Sum of the oxidation states of an element across several of its compounds
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Sub-topic 5
2024 · National Preliminary
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Oxidation state determination across two compounds
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Sub-topic 6
2026 · National One-Eighth
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Oxidation state determination across two compounds
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Sub-topic 7
2026 · National One-Eighth
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Balancing a disproportionation redox equation
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Sub-topic 8
2021 · National Preliminary
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Balancing half-reactions in acidic medium
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Sub-topic 9
2026 · National Preliminary
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Balancing half-reactions in acidic medium
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Sub-topic 10
2021 · National Preliminary
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Balancing a redox equation: sum of coefficients
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Sub-topic 11
2021 · National Preliminary
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Oxidation number of an unknown species in a compound
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Sub-topic 12
2021 · National Preliminary
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Riddle: perchloric acid and chlorine's +7 oxidation state
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Sub-topic 13
2026 · National Preliminary
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Oxidation states of fluorine, alkali metals and metal hydrides (true/false)
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Sub-topic 14
2026 · National Preliminary
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Oxidation states of fluorine, alkali metals and metal hydrides (true/false)
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Sub-topic 15
2024 · National One-Eighth
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Electrons in the reduction half-reaction of permanganate to mn2+
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Sub-topic 16
2026 · National One-Eighth
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Average oxidation state of sulfur in sodium thiosulfate (na2s2o3)
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Sub-topic 17
2024 · National Preliminary
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Oxidation state of manganese in permanganate and its reduction products by medium (true/false)
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Sub-topic 18
2023 · National Preliminary
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Oxidation states of chromium and carbon in given compounds (true/false)
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Sub-topic 19
2023 · National Preliminary
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Electrons transferred in the reduction of sulfate to sulfide
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Sub-topic 20
2023 · National Preliminary
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Moles of acid (h+) in the balanced oxidation half-reaction of cl2 to chlorate
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Sub-topic 21
2013 · National Preliminary
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Balancing a redox equation: permanganate oxidizing oxalate in acid
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Sub-topic 22
2013 · National Preliminary
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Balancing a redox equation: dichromate oxidizing iron(ii) in acid
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Sub-topic 23
2013 · National Preliminary
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Balancing the roasting equation of iron pyrites
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Sub-topic 24
2013 · National Preliminary
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Average oxidation state of sulfur in tetrathionate (true/false)
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Sub-topic 25
2013 · National Preliminary
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Unusual oxidation state of oxygen in hydrogen peroxide (true/false)
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Sub-topic 26
2013 · National Preliminary
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Maximum oxidation state of iodine in periodic acid (true/false)
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Sub-topic 27
2013 · National Quarterfinal
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Kmno4 oxidizes secondary alcohols to ketones (true/false)
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Sub-topic 28
2013 · National Quarterfinal
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Hot acidified kmno4 oxidizes toluene's methyl group to benzoic acid (true/false)
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Sub-topic 29
2013 · National Quarterfinal
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Toluene oxidation to benzoic acid does not require alkaline kmno4 (true/false)
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Sub-topic 30
2013 · National Quarterfinal
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Riddle: oxidation number, related to oxygen's electron-gaining tendency
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Sub-topic 31
2013 · National Semifinal
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Concentration of fe2+ from a permanganate titration
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Sub-topic 32
2013 · National Semifinal
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Minimum moles of h+ needed to complete a permanganate/iron(ii) reaction
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Sub-topic 33
2013 · National Semifinal
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Volume of dilute sulfuric acid needed with a 50% excess for a redox reaction
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Sub-topic 34
2016 · National One-Eighth
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Simply heating bauxite does not yield pure alumina; chemical processing is required (true/false)
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Sub-topic 35
2016 · National One-Eighth
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Manganese oxidation state of +3 in mn2o3 (true/false)
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Sub-topic 36
2016 · National One-Eighth
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Manganese oxidation state in k2mno4 is +6, and in kmno4 is +7 (not +8) (true/false)
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Sub-topic 37
2016 · National One-Eighth
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Mn(+7) is easily reduced to mn(+2) in acidic media (true/false)
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Sub-topic 38
2016 · National Preliminary
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Moles of dilute nitric acid reacting with copper (per the balanced equation producing no)
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Sub-topic 39
2016 · National Preliminary
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Mole ratio of sulfur to sulfuric acid when sulfur is oxidized by hot concentrated h2so4
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Sub-topic 40
2017 · National Quarterfinal
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Volume of kmno4 needed to react with a given volume/concentration of oxalate (2:5 ratio)
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Sub-topic 41
2017 · National Quarterfinal
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Volume of kmno4 needed to react with a given volume/concentration of fe2+ (1:5 ratio)
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Sub-topic 42
2017 · National Quarterfinal
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Concentration of iodine from a thiosulfate titration (1:2 ratio)
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Sub-topic 43
2019 · National Preliminary
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Balanced equation for aluminium reacting with hot moderately concentrated sulfuric acid
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Sub-topic 44
2020 · National One-Eighth
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Balanced equation for permanganate reduction by hydrogen peroxide in acid
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Sub-topic 45
2021 · National Preliminary
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Oxygen has oxidation state 0 in the ozone molecule, an elemental allotrope
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Sub-topic 46
2023 · National Preliminary
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Electrons involved in reducing sulfate ion to sulfide ion
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Sub-topic 47
2023 · National One-Eighth
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Oxidation half-reaction of sulfite to sulfate
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Sub-topic 48
2023 · National One-Eighth
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Reduction half-reaction of permanganate to mn2+
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Sub-topic 49
2023 · National One-Eighth
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Reduction half-reaction of fe3o4 to iron metal
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Sub-topic 50
2023 · National One-Eighth
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True or false: zero oxidation number implies the species is in its elemental form
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Sub-topic 51
2023 · National One-Eighth
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True or false: if oxidation numbers in a compound sum to zero, the compound is neutral
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Sub-topic 52
2023 · National One-Eighth
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True or false: a +2 oxidation-number sum in a polyatomic ion means it must be a cation
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