tbeck9982 tbeck9982 Today at 1:42 PM Chemistry Answered In the equation 2 H2 + O2 -> 2H2O, H2, O2, and H2O are all trace elements. Only H2O is a compound. Only H2 and O2 are compounds. H2, O2, and H2O are ALL elements. H2, O2, and H2O are ALL compounds.