Precipitation Reaction and Filtration for Insoluble Lead Sulfate Steps:

• Identify soluble salts providing Pb²⁺ and SO₄²⁻ ions for double displacement: Pb(NO₃)₂ + K₂SO₄ → PbSO₄ ↓ + 2KNO₃.
• Confirm PbSO₄ is insoluble in water per solubility rules (sulfates of Pb²⁺ are insoluble).
• Recognize the solid precipitate forms directly in solution without dissolving.
• Select filtration to separate the insoluble solid from the aqueous mixture.

Why D is correct:

• PbSO₄ has low solubility (Ksp ≈ 1.6 × 10⁻⁸), forming a pure precipitate from soluble lead nitrate and potassium sulfate, isolated by filtration.

Why the others are wrong:

• A: Lead chloride is sparingly soluble (~1 g/100 mL), leading to impure or incomplete reaction in aqueous solution.
• B: Crystallization requires evaporating a solution of the product, but insoluble PbSO₄ does not dissolve.
• C: Crystallization is incorrect for separating an insoluble precipitate like PbSO₄.

Final answer: D