Here, we will study those salts which are generally considered as insoluble in water. (e.g. AgCl, BaSO4, Ag2S, PbS etc) Actually no insoluble salt is actually completely insoluble, they have a very small solubility. Consider a vessel containing water with a sufficient amount of AgCl being put into it. A very small amount of it dissolves in water (because generally salts are composed of ions or contain polarised atoms). The small amount which is soluble is almost 100% ionised. For More Chemistry Formulas just check out main pahe of Chemsitry Formulas.
If the solubility of AgCl is x ¢ moles / l in the presence of 0.1M AgNO3, then