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 voltage is required
C. `Ag^(+)` ions are completely removed form solution
D. Less availability of `Ag^(+)` ions, as Cu cannot displace Ag from `[Ag(CN)_(2)]^(-)` ion.

Answer

D

Explanation

In the silver plating of copper, `K[Ag(CN)_(2)]` is used instead of `AgNO_(3)`. This is because if `AgNO_(3)` is used , Cu will displace `Ag^(+)` from `AgNO_(3)` . The deposit so obtained is black , soft , flaky and non-adhering . To get a good shining deposit `[Ag(CN)_(2)]^(-)` ions are used . As it is a stable complex, the concentration of `Ag^(+)` ions is very small in the solution. As such no displacent of `Ag^(+)` ions with Cu is possible.