In the silver plating of copper, `K[Ag(CN)_(2)]` is used instead of `AgNO_(3)` . The reason is

Options

A. a thin layer of Ag is formed on Cu
B. more voltaga is reqired
C. `Ag^(+)` ions are completely removed form solution
D. less availability of `Ag^(+)` ions, as Cu cannot displace Ag form `[Ag (CN)_(2)]^(-)` ion.

Answer

D

Explanation

Silver is used for plating articles of base-metals. The article to be plated is made the cathode while the anode consists of pure silver. The electrolyte is the solution of potassium argentocyanide. As the complex ion is very stable, the concentration of silver ion in solution is very small at any time
`[Ag (CN)_(2)]^(-) hArr Ag^(+) + 2CN^(-)`
Consequently, silver is deposite slowly and uniformly when electricitry is passed through the solution.