Separate test-tubes each contain solid barium carbonate and solid magnesium carbonate, and dilute hydrochloric acid is then added. Separate test-tubes each contain $0.1\,\text{mol dm}^{-3}$ barium chloride and $0.1\,\text{mol dm}^{-3}$ magnesium chloride, and dilute sodium hydroxide is then added. Which row is the correct one?