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Question:

The electrolytes usually used in the electroplating of gold and silver, respectively, are:

[Au(CN)2]⁻ and [Ag(Cl₂]⁻

[Au(CN)2]⁻ and [Ag(CN)2]⁻

[Au(OH)4]⁻ and [Ag(OH)2]⁻

[Au(NH3)2]+ and [Ag(CN)2]⁻

Solution:

The correct option is B: [Au(CN)2]⁻ and [Ag(CN)2]⁻
The anode is a bar of silver metal, and the electrolyte (the liquid in between the electrodes) is a solution of silver cyanide, [Ag(CN)2]⁻, in water. Gold plating is done in much the same way, using a gold anode and an electrolyte containing gold cyanide, [Au(CN)2]⁻. Option B is correct.