The maximum voltage can be produced in the cell which have higher difference in the electrocemical potential , in this case it would be most reactive magnesium and less reactive platinum...magnesum spontaneously gives its two electron and Pt takes its two electron.... as result generates the highest voltage
the only reason is because I looked online and the meaning for that is potassium hypochlorite my guy so if this is not right then I'm sorry but good luck.
