A double displacement reaction occurs between Barium Nitrate and Magnesium Sulfate, as shown below: Ba(NO₃)₂ ₍aq₎ + MgSO₄ ₍aq₎ → BaSO₄ ₍s₎ + Mg(NO₃)₂ ₍aq₎
Only the Barium ion (Ba²⁺) and the sulfate ion (SO₄²⁻) actually changed in terms of ionization as the rest of the ions are spectator ions.