A solution containing a mixture of metal cations was treated with dilute HClHCl and a precipitate formed. The solution was filtered, and H2SH2S was bubbled through the acidic solution. A precipitate again formed and was filtered off. Then, the pH was raised to about 88 and H2SH2S was again bubbled through the solution. This time, no precipitate formed. Finally, the solution was treated with a sodium carbonate solution, which resulted in the formation of a precipitate. Classify the metal ions based on whether they were definitely present, definitely absent, or whether it was possible they were present in the original mixture.

A solution containing a mixture of metal cations was treated with dilute HClHCl and a precipitate formed. The solution was filtered, and H2SH2S was bubbled through the acidic solution. A precipitate again formed and was filtered off. Then, the pH was raised to about 88 and H2SH2S was again bubbled through the solution. This time, no precipitate formed. Finally, the solution was treated with a sodium carbonate solution, which resulted in the formation of a precipitate.

Classify the metal ions based on whether they were definitely present, definitely absent, or whether it was possible they were present in the original mixture.