Question

When a metal rod $M$ is dipped into an aqueous colourless concentrated solution of $AgN{O}_3$, the solution turns light blue. Addition of aqueous $NaCl$ to the blue solution gives a white precipitate O. Addition of aqueous $N{H}_3$ dissolves $O$ and gives an intense blue solution.
The final solution contains:

• A. $\left[Pb\right(N{H}_3{)}_4{]}^{2+}$ and $[CoC{l}_4{]}^{2-}$
• B. $\left[Al\right(N{H}_3{)}_4{]}^{3+}$ and $\left[Cu\right(N{H}_3{)}_4{]}^{2-}$
• C. $\left[Ag\right(N{H}_3{)}_2{]}^{+}$ and $\left[Cu\right(N{H}_3{)}_4{]}^{2-}$
• D. $\left[Ag\right(N{H}_3{)}_2{]}^{+}$ and $\left[Ni\right(N{H}_3{)}_6{]}^{2+}$

Answer 1

The correct option is C $\left[Ag\right(N{H}_3{)}_2{]}^{+}$ and $\left[Cu\right(N{H}_3{)}_4{]}^{2-}$

The corresponding chemical reactions are:
$NaCl+AgN{O}_3\to \underset{O}{AgCl}+NaN{O}_3$
$2AgCl+2N{H}_3\left(aq\right)\to \underset{Soluble}{\left[Ag\right(N{H}_3{)}_2{]}^{+}}$
$Cu(N{O}_3{)}_2+4N{H}_3(aq)\to \underset{\text{deep blue colour}}{\left[Cu\right(N{H}_3{)}_4\left]\right(N{O}_3{)}_2}$