In general,thehigherthe valencyof the metal ion, the more stronglyboundthemetal ion is to the resin.Sincethe functional groupof theresinis a weakacid (COOH) anda weakbase(NH), hydronium ion (H3O+)competesstrongly with metalions for the chelatingsites.As a result,nitric acid at 0.5 to 2.0...