Sub-topic 1
2023 · National One-Eighth
Free
Riddle: silicon carbide (carborundum)
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Sub-topic 2
2023 · National One-Eighth
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Riddle: iridium, named for the rainbow
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Sub-topic 3
2023 · National One-Eighth
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Riddle: thallium, a semiconductor-adjacent metal
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Sub-topic 4
2021 · National Preliminary
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Riddle: chemical properties of matter
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Sub-topic 5
2025 · National One-Eighth
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Riddle: nickel
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Sub-topic 6
2026 · National Preliminary
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Riddle: nickel
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Sub-topic 7
2026 · National Preliminary
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Riddle: nickel
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Sub-topic 8
2026 · National Preliminary
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Riddle: nickel
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Sub-topic 9
2024 · National One-Eighth
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Reactivity of sodium with water compared to potassium, and its redox nature (true/false)
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Sub-topic 10
2024 · National One-Eighth
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Riddle: hydrochloric acid
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Sub-topic 11
2017 · National Quarterfinal
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Systematic (iupac) name of a polyatomic oxoanion
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Sub-topic 12
2026 · National One-Eighth
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Identifying reagents used in standard chemical tests (water detection, unsaturation)
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Sub-topic 13
2024 · Regional Championship
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Riddle: carbon monoxide, a colorless odorless linear gas
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Sub-topic 14
2024 · National Preliminary
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Riddle: calcium carbonate, an insoluble salt reactive with acids
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Sub-topic 15
2024 · National Preliminary
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Riddle: cobalt
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Sub-topic 16
2023 · National Preliminary
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Bonding character and brittleness of metalloids (true/false)
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Sub-topic 17
2023 · National Preliminary
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Riddle: iron, the most abundant element on earth by mass
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Sub-topic 18
2023 · National Preliminary
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Riddle: osmium, the densest element
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Sub-topic 19
2003 · National Semifinal
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Riddle: the periodic table of elements
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Sub-topic 20
2012 · National Preliminary
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Observation when hydrogen sulfide is bubbled through neutral iron(ii) solution
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Sub-topic 21
2012 · National Preliminary
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Collecting ammonia gas by downward displacement of air
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Sub-topic 22
2012 · National Preliminary
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Collecting hydrogen chloride gas by upward displacement of air
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Sub-topic 23
2012 · National Preliminary
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Riddle: uranium, a radioactive heavy metal
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Sub-topic 24
2013 · National Preliminary
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Sodium forms three distinct oxides under different conditions (true/false)
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Sub-topic 25
2013 · National Preliminary
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Nitrogen forms more than three distinct oxides (true/false)
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Sub-topic 26
2013 · National Quarterfinal
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Lindane's identity and synthesis route from benzene chlorination (true/false)
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Sub-topic 27
2013 · National Semifinal
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Riddle: sodium chloride, an ionic condiment
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Sub-topic 28
2014 · National Quarterfinal
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Elements found uncombined in nature (sulphur among sulphur/iron/magnesium)
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Sub-topic 29
2014 · National Quarterfinal
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Elements found uncombined in nature (gold and argon among gold/manganese/argon)
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Sub-topic 30
2014 · National Quarterfinal
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Elements found uncombined in nature (carbon among mercury/sodium/carbon)
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Sub-topic 31
2014 · National Quarterfinal
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Sodium carbonate resists thermal decomposition under ordinary heating (true/false)
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Sub-topic 32
2014 · National Quarterfinal
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Lead(ii) carbonate paint blackening via lead sulfide formation (true/false)
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Sub-topic 33
2016 · National One-Eighth
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Iron(ii) sulfide colour is black, not blue (true/false)
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Sub-topic 34
2016 · National One-Eighth
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Aluminium cookware use is not linked to proven poisoning (true/false)
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Sub-topic 35
2016 · National One-Eighth
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Riddle: bromine, the only liquid non-metal element
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Sub-topic 36
2016 · National One-Eighth
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Riddle: tin (sn), from latin 'stannum', extracted from cassiterite
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Sub-topic 37
2017 · National Semifinal
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Balancing the equation for arsenic dissolving in fused sodium hydroxide
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Sub-topic 38
2017 · National Semifinal
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Balancing the equation for tellurium(iv) oxide reacting with hydrogen iodide
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Sub-topic 39
2017 · National Quarterfinal
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Recovering gold from a cyanide complex by zinc displacement
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Sub-topic 40
2017 · National Quarterfinal
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Recovering gold from amalgam by heating, and the mercury vapour health hazard
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Sub-topic 41
2018 · National Preliminary
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Thermal decomposition products of lead(ii) nitrate
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Sub-topic 42
2020 · National One-Eighth
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Balanced equation for phosphorus(v) oxide reacting with water
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Sub-topic 43
2021 · National Quarterfinal
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True or false: heating solid zn(oh)2 forms zno
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Sub-topic 44
2021 · National Quarterfinal
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True or false: zno is yellow when hot and white when cold
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Sub-topic 45
2022 · National Preliminary
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Riddle: sulphur, a nonmetal by-product of fossil fuel refining with several allotropes
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Sub-topic 46
2022 · National Preliminary
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Riddle: diamond, the hardest natural substance, a single-element gem
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Sub-topic 47
2022 · National Preliminary
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Riddle: potassium chloride, a metal halide used as a potash fertilizer
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Sub-topic 48
2023 · National Preliminary
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Riddle: silver chloride, a light-sensitive coinage-metal halide
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