Lead and barium sulfate are insoluble, while silver calcium sulfate is slightly soluble.
Only potassium, sodium, ammonium and barium are soluble in alkali, and calcium hydroxide is slightly soluble.
Ok, we still need a few. This is for my junior high school. I suggest that the landlord remember from the way of understanding that the solid does not dissolve because the ions of the solid have great interaction, so it is not easy to dissolve in water. The interaction between solids (actually referring to the interaction between ionic crystals here) depends on two factors: charge and radius, of which charge has the greatest influence. The bigger the charge, the easier it is to precipitate, and the more radius matching, the easier it is to precipitate. These two charges are medium and large. But if you scrutinize it carefully, you will find that ferric halides are all soluble in water, which is not in line with what I said earlier, because ferric ions are also easy to hydrate, that is to say, they are closely combined with crystals and water. That is to say, solubility is actually to compare the binding ability of ions with crystals and with water. For general main group ions, the binding ability with water is very poor, and the explanation for this involves orbitals, which is easy for transition elements. Therefore, the high-valent ions of excess elements are not necessarily insoluble, because water has a strong affinity for them. There is a special case here, which is hydroxyl. Remember that hydroxyl groups are very similar to water, and hydrophilic ones are generally more intimate, so the hydroxide of transition elements basically precipitates, while the main group, the first main group and the second main group basically do not precipitate, except beryllium, magnesium and calcium. Because the radius is too small, the charges of the three groups basically precipitate. Well, that's basically it. In addition, you can try to recite the periodic table of elements, which is actually very easy to recite. Compare the periodic table of elements and mark the solubility of each of their different compounds. According to the order of chloride, sulfate and hydroxide, it will be clear at a glance soon. Please contact me if you have any questions.