Determine the oxidation number of each element for the following substances and arrange these substances in decreasing order of strength as oxidizing agents at the standard-state conditions of concentration.
H3AsO4, Cr2+, O3, V3+, S4O62-
Determine the oxidation number of each element for the following substances and arrange these substances in decreasing order of strength as reducing agents at the standard-state conditions of concentration.
Al, H2C2O4, Fe(CN)64-, Se, Zn