Meanings

aluminium hydroxide (aluminum)

fermented milk drink (e.g. Yakult, Calpis, Calpico)

carbonic acid gas

oxygen mask

to say time and time again

nitrogen oxide (esp. nitric oxide, but also nitrous oxide, nitrogen dioxide, dinitrogen pentoxide, etc.)

oxygen tent

barium sulfate (BaSO4) (sulphate)

potassium dichromate-sulfuric acid solution

oxyacetylene flame

reactive oxygen (i.e. free radicals, which can be destructive at high concentrations)

arsenic trioxide

manganese dioxide (MnO2)

lead chromate (PbCrO4)

calcium carbonate (CaCO3)

oxoacid

mercurous oxide (Hg2O)

barium oxide (BaO)

potassium dichromate (K2Cr2O7)

H2O2