861 past contests
Topic 25 · Free-radical bromination product of butane, favoring the more stable secondary radical
Topic 3 · Strongest and weakest acids among hbro, hbr, hbro2
Topic 3 · Strongest and weakest acids among hclo, hbro, hio
Topic 3 · Strongest and weakest acids among hclo, hclo2, hclo3
Topic 29 · True or false: allotropes arise from differences in neutron number or atomic radii
Topic 32 · True or false: physical/chemical properties and states of allotropes
Topic 5 · Riddle: formaldehyde, the simplest aldehyde used to preserve dead organisms
Topic 15 · True or false: enzymes may be denatured during catalytic reactions
Topic 15 · True or false: enzymes help produce more product during chemical reactions
Topic 15 · True or false: enzymes may catalyze both forward and backward reactions
Topic 3 · Strontium nitrate solution is neutral (strong acid, strong base salt)
Topic 9 · Sum of reactant coefficients in balanced complete combustion of benzene
Topic 3 · Ammonium ethanoate solution is neutral (weak acid, weak base with similar ka/kb)
Topic 1 · Mass of carbon in a given mass of 2-hexene
Topic 1 · Mass of a metal(ii) oxide from the metal's atomic mass, correcting the assumed m2o formula
Topic 3 · Sodium phosphate solution is basic (weak acid, strong base salt)
Topic 27 · Protons, neutrons and electrons in cobalt-59
Topic 27 · Protons, neutrons and electrons in chromium-55
Topic 27 · Protons, neutrons and electrons in copper-65
Topic 6 · True or false: a decomposition reaction may involve both chemical and physical changes