When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N, the solution turns light blue. Addition of aqueous `NaCl` to the blue solution gives a white precipitate O. Addition of aqueous `NH_(3)` dissolves O and gives an intense blue solution.
The metal rod M is

Options

A. `[Pb(NH_(3))_(4)]^(2+)` and `[CoCl_(4)]^(2+)`
B. `[Al(NH_(3))_(4)]^(3+)` and `[Cu(NH_(3))_(4)]^(2+)`
C. `[Ag(NH_(3))_(2)]^(+)` and `[Cu(NH_(3))_(4)]^(2+)`
D. `[Ag(NH_(3))_(2)]^(+)` and `[Ni(NH_(3))_(6)]^(2+`

Answer

c

Explanation

The addition of NaCl to the blue solution gives a white precipitate AgCl. It dissolves in aqueous ammonia to form a complex containing
`[Ag(NH_3)_2]^(+)` and `[Cu(NH_3)_4]^(2+)`
It is intense blue colour.