Identify the oxidising agent (oxidant) in the following reactions
`{:((a), Pb_(3)O_(4) + 8HCl to 3PbCl_(2) + Cl_(2) + 4H_(2)O, (b), 2Ca + O_(2) to 2CaO.),((c), CuSO_(4) + Zn to Cu + ZnSO_(4), (d), V_(2)O_(5) + 5Ca to 2V + 5CaO),((e), 3Fe + 4H_(2)O to Fe_(3)O_(4) + 4H_(2), (f), ZnO + H_(2) to Zn + H_(2)O):}`
