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.
$1.$ The metal rod $M$ is
$(A)$ $Fe$ $(B)$ $Cu$ $(C)$ $Ni$ $(D)$ $Co$
$2.$ The compound $N$ is
$(A)$ $AgNO_3$ $(B)$ $Zn(NO_3)_2$
$(C)$ $Al(NO_3)_3$ $(D)$ $Pb(NO_3)_2$
$3.$ The final solution contains
$(A)$ $[Pb(NH_3)_4]^{2+}$ 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 $[Ni(NH_3)_6]^{2+}$
Give the answer for questions $1$,$2$ and $3$.

• A
  $(B, A, C)$
• B
  $(A, B, C)$
• C
  $(A, B, D)$
• D
  $(B, C, D)$