Look at the reaction. cap h sub 2 SO sub 4 A q plus Mg times s rightarrow MgSO sub 4 times A q plus cap h sub 2 of g Which substance is the acid in the reaction?

Sulfuric acid, H₂SO₄(aq), is the acid in this reaction. It donates hydrogen ions as it reacts with magnesium, forming hydrogen gas and magnesium sulfate. Therefore, the correct choice is H₂SO₄(aq).

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