2. Which of the following compounds would form a precipitate? a. KNO3 b. CaCO3 c. KI d. Sr(OH)2

To determine which compound would form a precipitate, we need to consider the solubility rules for ionic compounds in water.<br /><br />a. $KNO3$ (potassium nitrate) is soluble in water, so it would not form a precipitate.<br /><br />b. $CaCO3$ (calcium carbonate) is insoluble in water, so it would form a precipitate.<br /><br />c. KI (potassium iodide) is soluble in water, so it would not form a precipitate.<br /><br />d. $Sr(OH)2$ (strontium hydroxide) is soluble in water, so it would not form a precipitate.<br /><br />Therefore, the correct answer is b. $CaCO3$.