Precipitates from magnesium ion reactions Steps:

• Identify magnesium sulfate as MgSO4(aq), providing Mg2+ ions.
• Recall solubility rules: Mg2+ forms white precipitates with OH-, CO3 2-, PO4 3-, and C2O4 2- (e.g., Mg(OH)2, MgCO3).
• Assume the shown solutions include three that provide these anions (e.g., NaOH, Na2CO3, Na3PO4) and one that does not (e.g., NaCl).
• Count matching solutions: three produce white Mg precipitates.

Why D is correct:

• Three solutions contain anions forming insoluble white magnesium salts, per solubility rules.

Why the others are wrong:

• A: All three reactive solutions are present.
• B: Underestimates; two more form precipitates.
• C: Misses the third reactive solution.

Not enough information on exact solutions shown.

Final answer: D