Final answer:
Sulfuric acid (H₂SO₄) option D, liberates hydrogen when reacting with metals and forms a white precipitate of barium sulfate with aqueous barium nitrate, making it the compound referred to as compound X in the question.
Step-by-step explanation:
The compound that reacts with metals to liberate hydrogen and forms white precipitate with aqueous barium nitrate is sulfuric acid (H₂SO₄). When sulfuric acid reacts with metals such as zinc or iron, it liberates hydrogen gas and forms a corresponding sulfate salt. This behavior is commonly used in the production of fertilizers. Moreover, the reaction of sulfuric acid with barium chloride can be represented by the following equation: BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl, where BaSO₄ is barium sulfate, a white precipitate that is insoluble in water and does not dissolve in hydrochloric acid (HCl).