861 past contests
Topic 6 · Equilibrium constant kc with correct units from equilibrium concentrations
Topic 19 · Molecular formula of a compound from percentage composition
Topic 26 · Systematic name of an alkyl-substituted bromoalkane isomer
Topic 8 · Riddle: carbon-12
Topic 37 · Distinguishing alloys from chemical compounds (true/false)
Topic 35 · Properties of alkali metals: melting point, atomic radius and reactivity trends (true/false)
Topic 26 · Problem of the day: naming structural isomers of a bromo-substituted alkene
Topic 7 · Electrons in the reduction half-reaction of permanganate to mn2+
Topic 3 · Ph of a strong diprotic base solution from a given mass and volume
Topic 19 · Percentage yield from a given mass of product
Topic 4 · Stages of the water treatment process
Topic 5 · Effect of increasing molar mass on physical properties of alkanes
Topic 28 · Possible quantum numbers (n, l, ml) for a given subshell
Topic 5 · Riddle: chloroform
Topic 3 · Composition and behaviour of buffer solutions (true/false)
Topic 35 · Periodic trends in melting point and intermolecular forces down group 17 (true/false)
Topic 1 · Molar mass of a named ionic compound
Topic 12 · Volume of acid required to neutralize a base of known volume and concentration
Topic 19 · Percentage composition by mass in a compound
Topic 4 · Types of water-induced soil erosion