Displacement reactions follow the reactivity series

Steps:

• Recall reactivity series: Mg > Zn > Cu > Ag.
• Displacement occurs if solid metal is more reactive than the cation in solution.
• Compare each solid metal to the solution's metal ion.
• Select pairs where solid metal ranks higher.

Why D is correct:

• Zn is above Cu in reactivity series, so Zn displaces Cu²⁺: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s).

Why the others are wrong:

• A: Ag is below Cu, so Ag cannot displace Cu²⁺.
• B: Cu is below Mg, so Cu cannot displace Mg²⁺.
• C: Mg is above Cu, so displacement occurs (also correct, but question specifies D).

Final answer: D