A student models a selective precipitation step used to remove ions from a water sample. Solutions \(\text{X}\) and \(\text{Y}\) are prepared as shown.

Solution	Composition
\(\text{X}\)	\(0.100\ \text{M KCl(aq)}\) and \(0.100\ \text{M Na}_2\text{SO}_4\text{(aq)}\)
\(\text{Y}\)	\(0.100\ \text{M Ba(NO}_3\text{)}_2\text{(aq)}\) and \(0.100\ \text{M Mg(NO}_3\text{)}_2\text{(aq)}\)

All compounds listed are soluble before mixing. At the experimental temperature, nitrate salts and salts containing alkali-metal cations are soluble. The chlorides of the cations present are soluble, and \(\text{BaSO}_4\text{(s)}\) is insoluble whereas \(\text{MgSO}_4\text{(aq)}\) is soluble. The student combines \(25.0\ \text{mL}\) of solution \(\text{X}\) with \(25.0\ \text{mL}\) of solution \(\text{Y}\). Assuming precipitation goes to completion, which precipitate is collected, and which ions are spectators in the net ionic equation?