861 past contests
Topic 14 · True or false: zno is yellow when hot and white when cold
Topic 27 · Riddle: tritium, the radioactive hydrogen isotope that decays to helium-3
Topic 34 · True or false: ca2+ solutions give no precipitate with dilute naoh or h2s
Topic 15 · True or false: second order reactions must involve at least two reaction steps
Topic 14 · True or false: heating solid zn(oh)2 forms zno
Topic 15 · True or false: second order reactions always involve two different reactant molecules
Topic 15 · True or false: the rate constant can numerically equal the rate under certain conditions
Topic 8 · Helium is preferred over argon for balloons because it is far less dense
Topic 25 · Balanced combustion equation for hexanol in excess air, correcting a wrong molecular formula
Topic 33 · Canned food is called tinned food because the cans are coated with tin metal
Topic 25 · Balanced combustion equation for heptane in excess air
Topic 25 · Balanced combustion equation for 3-octanone in excess air
Topic 30 · Three elements named after countries: germanium, polonium, francium
Topic 2 · Counting pi bonds in sulfuric acid from its two s=o double bonds
Topic 23 · Phenol is more acidic than ethanol due to resonance-stabilization of the phenoxide ion
Topic 3 · Arrhenius acids raise [h+] in water, while bronsted-lowry acids donate a proton in any medium
Topic 39 · Identifying which metal releases hydrogen from dilute acid via its electrode potential
Topic 6 · Equilibrium concentrations of butane and isobutane from mass balance in an isomerization
Topic 20 · Concentration of mg2+ ions from dissolving a hydrated magnesium sulfate mass
Topic 27 · Atoms of an element with different mass numbers are isotopes of each other