the common metallic elements have been invetigated for their relative reactivities and have been arranged into what is called electromotive series. Explain the series in terms of choosing the suitable electrode in setting up an electrochemical series.
Your question isn't clear at all as to what you are asking; however, the activity series (EMF series) arrangement is this. An element in the series will displace the ion of another element below it in the series. Therefore, Al will displace Pb^2+, Zn will displace H^+ etc.
