Relatively {HEAD ~ base metals} such as {TAIL ~ lead} and cadmium, specifically, may pass into solution in aqueous and especially in increasingly acid environment, decomposing water and liberating hydrogen 
Relatively { HEAD ~ base metals } such as { TAIL ~ lead } and cadmium , specifically , may pass into solution in aqueous and especially in increasingly acid environment , decomposing water and liberating hydrogen
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH