Discussion Forum



1)

When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N, the solution turns light blue. The addition of aqueous NaCl to the blue solution gives a white precipitate O. Addition of aqueous NH3 dissolves O and gives an intense blue solution

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 $[Co(NH_{3})_{4}]^{2+}$

D) $[Ag(NH_{3})_{2}]^{+}$ and $(Ni(NH_{3})_{6}]^{2+}$

Answer:

Option C

Explanation:

Since in the beginning, concentrated AgNO3 solution was taken some AgNO3 remain in  solution gives precipitate of $AgCl$ on addition of NaCl. The precipitate finally  dissolve in ammonia and Cu2+ present in solution forms complex with ammonia as

    $Cu(NO_{3})_{2}+4NH_{3}(aq) \rightarrow   [Cu(NH_{3})_{4}]^{2+}+2NO_{3}$

                                                                        Blue

$AgCl(s)+2NH_{3}(aq) \rightarrow  [Ag(NH_{3})_{2}]^{+}+Cl^{-}$