In the following reaction sequence in aqueous solution, the species X, Y and Z, respectively are?S2O32−→Ag+XClearSolution→Ag+YWhitePrecipitate→lime waterYBlackPrecipitate

Na2S2O3+Ag+→AgS2O32−3→Ag+Ag2S2O3→∆Ag2SIn presence of excess of hypo, formation of soluble complex takes place. If silver is in excess, a white precipitate of silver thiosulfate is formed. On heating the resultant aqueous suspension, a black precipitate of silver sulfide is obtained.