Reactions of copper compounds with sulfuric acid Steps:

• Copper(II) sulfate forms from sulfuric acid reacting with copper compounds, followed by crystallization for purity.
• Method 1: Cu + H₂SO₄ (dilute) does not react, as copper is below hydrogen in the reactivity series.
• Methods 2 and 3: CuCO₃ + H₂SO₄ → CuSO₄ + CO₂ + H₂O; CuO + H₂SO₄ → CuSO₄ + H₂O, both produce clear solutions.
• Method 4: CuSO₄ is soluble, so precipitation yields no solid product. Why C is correct:
• Methods 2 and 3 use acid-base neutralization (CuCO₃ or CuO + H₂SO₄) to form soluble CuSO₄, filtered and evaporated for pure crystals. Why the others are wrong:
• A includes method 1, which fails due to low reactivity of copper.
• B includes method 1 and omits method 2, missing a valid reaction.
• D includes methods 1 and 4, neither suitable for CuSO₄ preparation.

Final answer: C