Which metal ions forms insoluble compounds?

Several metal ions form insoluble compounds, including lead (Pb²⁺), Mercury (Hg²⁺), silver (Ag⁺), and barium (Ba²⁺). These ions tend to create insoluble salts with common anions such as chloride (Cl⁻), sulfate (SO₄²⁻), and carbonate (CO₃²⁻). For instance, silver chloride (AgCl), barium sulfate (BaSO₄), and lead(II) carbonate (PbCO₃) are well-known insoluble compounds. The solubility of metal ions can vary based on specific conditions and the presence of complexing agents.