Question: are hydroxides soluble or insoluble?
Answer: hydroxides OH- are insoluble except the slightly soluble Ca(OH)2, and the soluble salts of Group 1 metals and ammonium, and Sr and Ba from Group 2. most phosphates PO43- and carbonates - CO32- are insoluble except salts of Group 1 metals and ammonium, NH. all oxides are insoluble except those of Group IA metals.