Solubility differences in Group 2 salts Steps:

• Test 1 adds SO₄²⁻; BaSO₄ has low Ksp (1.1 × 10⁻¹⁰), forms precipitate; MgSO₄ is soluble, no precipitate.
• Test 2 adds OH⁻; Mg(OH)₂ has low Ksp (5.6 × 10⁻¹²), forms precipitate; Ba(OH)₂ has higher Ksp (2.6 × 10⁻³), remains soluble, no significant precipitate.
• Same ion concentrations mean precipitate amount depends on solubility; Ba²⁺ gives more in test 1, Mg²⁺ gives more in test 2.
• Option A matches these observations.

Why A is correct:

• BaSO₄ insolubility (Ksp << product) ensures precipitate in test 1; Mg(OH)₂ insolubility (Ksp << [Mg²⁺][OH⁻]²) ensures precipitate in test 2, while Ba(OH)₂ solubility prevents it.

Why the others are wrong:

• B: Ba(OH)₂ is soluble, so less/no precipitate with Ba²⁺ in test 2.
• C: MgSO₄ is soluble, so no precipitate with Mg²⁺ in test 1.
• D: Reverses both; ignores BaSO₄ insolubility and MgSO₄ solubility.

Final answer: A