861 past contests
Topic 27 · Sum of protons, electrons and neutrons in the most stable isotope of sodium
Topic 6 · Solubility product of iron(ii) hydroxide from its fe2+ concentration
Topic 6 · Maximum chloride concentration to precipitate lead(ii) chloride, from ksp
Topic 25 · True or false: alkanes undergo electrophilic substitution reactions
Topic 5 · Possible structures for the organic compound c4h6 (2 degrees of unsaturation)
Topic 25 · True or false: alkanes undergo electrophilic addition reactions
Topic 25 · True or false: alkanes undergo nucleophilic addition reactions
Topic 6 · True or false: changing product concentration changes the equilibrium constant
Topic 6 · True or false: changing pressure changes the equilibrium constant
Topic 6 · True or false: changing temperature changes the equilibrium constant
Topic 9 · Sum of stoichiometric coefficients in balanced h2s+ag(nh3)2oh→h2o+nh3+ag2s
Topic 28 · Complete quantum numbers for a valence electron of beryllium
Topic 28 · Complete quantum numbers for a valence electron of sodium
Topic 28 · Complete quantum numbers for a valence electron of carbon
Topic 19 · Percentage by mass of oxygen in methanol (ch4o)
Topic 40 · Identifying the reducing/oxidizing agent in three redox equations (clo3-+i-, h2s+cl2, fe3o4+al)
Topic 30 · Scientists who discovered the neutron, electron and proton
Topic 14 · Riddle: potassium chloride, a metal halide used as a potash fertilizer
Topic 14 · Riddle: diamond, the hardest natural substance, a single-element gem
Topic 3 · True or false: fluoride is a stronger base than chloride