861 past contests
Topic 20 · Mass of solute required to prepare a solution of a given volume and molarity
Topic 9 · Balancing equations: sum of coefficients
Topic 11 · Partial pressure of a gas in a mixture using mole fraction
Topic 2 · Bonding and hybridization in graphite, silicon dioxide and graphene (true/false)
Topic 21 · Composition of crude petroleum and natural gas, and fractional distillation (true/false)
Topic 14 · Riddle: nickel
Topic 6 · Solubility and polarity: like-dissolves-like, ionic compound solubility, and solvent amount (true/false)
Topic 5 · Molecular formula from percentage composition and molar mass
Topic 6 · Solubility product: concentration from ksp, common-ion suppressed solubility, and ionic product after mixing
Topic 1 · Finding an unknown atomic mass from a compound's mass and moles
Topic 34 · Physical state and color of the halogens (cl2, br2, i2) at room temperature
Topic 5 · Riddle: dichloromethane, a chlorinated organic solvent
Topic 25 · Free-radical halogenation: initiation conditions, unpaired electrons and homolytic fission (true/false)
Topic 29 · Periodic trends in first ionization energy and isoelectronic ionic radii (true/false)
Topic 26 · Systematic name for a structural isomer of butane (2-methylpropane)