Identify A and B respectively in the following reactions :
`4Au(s)+8CN^(-) (aq)+2H_(2)O (aq) overset(O_(2)(g))(rarr) A(aq)+4 OH^(-) (aq) overset(Zn (s))(rarr) B+2 Au (s)`

Options

A. `[Au(CN)_(2)]^(-), [Zn(CN)_(4)]^(2-)`
B. `Au(CN)_(4), [Zn(CN)_(4)]^(2-)`
C. `HCN, [Au(CN)_(4)]^(2-)`
D. `AuCN, [HCN]`

Answer

A

Explanation

In the given reaction, (A) and (B) are respectively : `[an(CN)_(2)]^(-)` and `[Zn(CN)_(4)]^(2-)`
The whole reaction is as follows :
`4Au+8 CN^(-) (aq) +2H_(2)O(aq) overset(O_(2)(g))(rarr) underset((A))(4[Au(CN)_(2)]^(-))+2H_(2)O overset(Zn (s))(rarr) underset((B))(2[Zn(CN)_(4)]^(2-))+2Au`