Question

After the precipitation of the Group I cations as chlorides by the reaction with HCl, nearly all of the precipitate dissolves in hot water. Which ion(s) are present? Which ion(s) are absent?

Answer 1

Group I is Ag, Hg(+1), Pb.
PbCl2 is soluble in hot water. AgCl and Hg2Cl2 are not.
So ???? must be the ppt.