Metal Reactivity and Corrosion Properties

Steps:

• Recall reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Cu > Ag > Au.
• Assess corrosion: Noble metals like Au and Ag resist oxidation.
• Check displacement: More reactive metal displaces less reactive from solution.
• Compare electron tendencies: More reactive metals oxidize (lose electrons) easier.

Why B is correct:

• Gold and silver are noble metals with very negative reduction potentials (Ag: +0.80 V, Au: +1.50 V), resisting corrosion by not readily forming oxides, making them durable for jewelry.

Why the others are wrong:

• A: Copper forms a protective oxide but remains reactive, slowly corroding in moist air.
• C: Aluminium (below Mg in reactivity series) cannot displace magnesium ions; Mg displaces Al.
• D: Magnesium, more reactive than Zn, loses electrons more readily in oxidation; Zn2+ ions gain electrons easier than Mg2+.

Final answer: B