Solubility differences in group 2 hydroxides and sulfates

Steps:

• NaOH reacts with MgCl₂ to form insoluble Mg(OH)₂ white precipitate.
• NaOH reacts with BaCl₂ to form soluble Ba(OH)₂ colourless solution.
• Excess H₂SO₄ dissolves Mg(OH)₂ into soluble MgSO₄ colourless solution.
• Excess H₂SO₄ reacts with Ba(OH)₂ to form insoluble BaSO₄ white precipitate.

Why B is correct:

• B matches observations: colourless solution for MgCl₂ (MgSO₄ soluble) and white precipitate for BaCl₂ (BaSO₄ insoluble), per solubility rules for group 2 compounds.

Why the others are wrong:

• A: Predicts solutions for both, but ignores BaSO₄ precipitation.
• C: Reverses results; Mg(OH)₂ dissolves, while BaSO₄ forms precipitate.
• D: Predicts precipitates for both, but MgSO₄ remains soluble.

Final answer: B