861 past contests
Topic 1 · Problem of the day: mass of a limiting-reagent product across a two-step synthesis with fractional yields
Topic 2 · Hardness of diamond from its covalent tetrahedral lattice
Topic 2 · Softness of graphite from its layered structure and weak interlayer forces
Topic 4 · Hydrofluorocarbons as cfc replacement refrigerants
Topic 4 · Role of chlorofluoromethanes in stratospheric ozone depletion
Topic 5 · The carbonyl functional group of alkanones (ketones)
Topic 22 · Classifying an amine as primary, secondary or tertiary from its substitution
Topic 8 · Identifying the periodic table group of an element from its atomic number
Topic 29 · Trend of atomic radius and atomic number across a period (b, c, n, o)
Topic 3 · Bronsted-lowry vs arrhenius bases, and temperature/dilution effects on acid ph and ionization (true/false)
Topic 9 · Balancing equations: sum of coefficients
Topic 10 · Mass of a sample from heat absorbed, temperature change and specific heat capacity
Topic 19 · Mass of pure solute in a solution from its percentage by mass and density
Topic 37 · Riddle: brass, an alloy of copper and zinc
Topic 1 · Total volume from combining several measured volumes of solution
Topic 1 · Chemical formula of an ionic compound from its name
Topic 39 · Emf of a cell from two standard reduction potentials