MgCO3: Increasing acidity will cause the following reaction: MgCO3(s) + 2H+ ==> Mg(2+) + H2O + CO2(g) and thus the solubility will increase. AgI: Increasing acidity will NOT affect the solubility. CuS: Increasing acidity will cause the following reaction: CuS(s) + 2H+ ==> Cu(2+) + H2S(g) and thus the solubility will increase. PbBr2: Increasing acidity will NOT affect the solubility. Ba(OH)2 The solubility of Ba(OH)2 in water is only 5.6 g/100 g. By acidifying the solution, the following reaction take place: H+ + OH- ==> H2O and thus [OH-] would drop, and thus Ba(OH)2 solubility would be increased. Solution MgCO3: Increasing acidity will cause the following reaction: MgCO3(s) + 2H+ ==> Mg(2+) + H2O + CO2(g) and thus the solubility will increase. AgI: Increasing acidity will NOT affect the solubility. CuS: Increasing acidity will cause the following reaction: CuS(s) + 2H+ ==> Cu(2+) + H2S(g) and thus the solubility will increase. PbBr2: Increasing acidity will NOT affect the solubility. Ba(OH)2 The solubility of Ba(OH)2 in water is only 5.6 g/100 g. By acidifying the solution, the following reaction take place: H+ + OH- ==> H2O and thus [OH-] would drop, and thus Ba(OH)2 solubility would be increased..