861 past contests
Topic 3 · Conjugate acid and conjugate base of a given species
Topic 2 · Molecular polarity of boron trifluoride, silicon tetrafluoride, and phosphorus trichloride (true/false)
Topic 14 · Riddle: osmium, the densest element
Topic 6 · Inferring reaction composition and phase from an equilibrium expression (true/false)
Topic 3 · Problem of the day: ph, percentage dissociation and buffer formation for a weak monobasic acid
Topic 3 · Ph of a weak monoprotic acid solution from its molarity and pka
Topic 7 · Moles of acid (h+) in the balanced oxidation half-reaction of cl2 to chlorate
Topic 2 · Vsepr shapes of covalent fluorides from central-atom electron domains (linear, bent, planar, pyramidal)
Topic 3 · Molecular formula of the conjugate base of an alcohol, carboxylic acid, or phenol
Topic 4 · Riddle: water vapor, the most abundant greenhouse gas
Topic 29 · Atomic number is not simply proportional to density, atomic size, or discovery order (true/false)
Topic 12 · Percentage purity from a neutralisation reaction
Topic 1 · General properties of decomposition reactions (true/false)
Topic 7 · Electrons transferred in the reduction of sulfate to sulfide
Topic 20 · Concentration of a solution from mass of solute and volume
Topic 5 · Systematic name of a carbonyl compound from its molecular formula
Topic 2 · Riddle: ice, less dense than liquid water
Topic 29 · Periodic trends in first ionization energy and isoelectronic ionic radii (true/false)
Topic 6 · Effect of pressure on chemical equilibrium position (true/false)
Topic 2 · Standard enthalpy of combustion from standard enthalpies of formation (hess's law)