Question

White ppt. in (c) and the soluble complex formed from white ppt. with the hypo solution is/are___________.

• A. $Pb(OH{)}_2$, $\left[Pb\right(S_2{O}_3{)}_2{]}^{2-}$
• B. $A{g}_{2}O$, $\left[Ag\right(S_2{O}_3{)}_2{]}^{3-}$
• C. $HgO.Hg\left(N{H}_2\right)N{O}_3$, $\left[Hg\right(S_2{O}_3{)}_2{]}^{2-}$
• D. None of these

Answer 1

The correct option is C $HgO.Hg\left(N{H}_2\right)N{O}_3$, $\left[Hg\right(S_2{O}_3{)}_2{]}^{2-}$

For test tube "a"
If it contains $C{d}^{2+}$ then
$\begin{array}{ccc}C{d}^{2+}& \underset{Solution}{\overset{N{H}_3}{\to }}& Cd(OH{)}_2\downarrow \\ & & \left(W\right)\\ & & \downarrow ExcessofN{H}_{3}solution\\ & & \left[Cd\right(N{H}_3{)}_4{]}^{2+}\\ & & Colorlesssolution\end{array}$
If it contains $Z{n}^{2+}$ then
$\begin{array}{ccccc}Z{n}^{2+}& \underset{solution}{\overset{N{H}_3}{\to }}& Zn(OH{)}_2& \underset{ofN{H}_{3}solution}{\overset{Excess}{\to }}& \left[Zn\right(N{H}_3{)}_4{]}^{2+}\\ & & & & \left(colorlesssolution\right)\end{array}$
For test tube "b"
$\begin{array}{ccccc}Z{n}^{2+}& \underset{Solution}{\overset{N{H}_3}{}}& Zn(OH{)}_2\downarrow & \stackrel{\Delta }{\to }& ZnO\\ & \left(white\right)& & & (White:cold)\\ & & & & (Yellow:cold)\end{array}$
For test tube "c"
If it contains $Hg2+$ then