Selective precipitation of barium sulfate

Steps:

• Dissolve ore in nitric acid to form soluble Mg(NO₃)₂ and Ba(NO₃)₂.
• Add H₂SO₄(aq) to precipitate insoluble BaSO₄ while Mg²⁺ remains in solution as soluble MgSO₄.
• Filter the solid BaSO₄ to isolate barium compound.
• Evaporate or process filtrate to obtain magnesium compound.

Why C is correct:

• BaSO₄ is insoluble (Ksp = 1.1 × 10⁻¹⁰), allowing selective precipitation of barium, while MgSO₄ is soluble.

Why the others are wrong:

• A: BaCl₂ is soluble, so no barium precipitate forms.
• B: MgCl₂ is soluble, so no magnesium precipitate forms.
• D: MgSO₄ is soluble, so no magnesium precipitate forms.

Final answer: C