Question

Compound $\left(\right.P\left.\right)$ forms a precipitate with $AgNO_{3}$ . The precipitate dissolves in excess reagent $\left(\right.P\left.\right).\left(\right.P\left.\right)$ cannot be :

• A. $KOH$
• B. $KCN$
• C. $Na_{2}S_{2}O_{3}$
• D. $NH_{3}$

Answer 1

Answer: (A)

$=\left(\right.1\left.\right)2\left(AgNO\right)_{3}+2KOH \rightarrow \left(Ag\right)_{2}O\downarrow\left(\right.\text{ black }\left.\right)+2\left(KNO\right)_{3}+H_{2}O$
$\downarrowexcessKOH$
No reaction
$\text{ (2) }\left(AgNO\right)_{3}\overset{\left(CN\right)^{-}}{ \rightarrow }\text{ AgCN }\downarrow\text{ (white) }\frac{\left(CN\right)^{-}}{\text{excess }}Ag\left(\right.CN\left.\right)_{2}^{-}$
(Soluable)
$\text{ (3) }\left(AgNO\right)_{3}\overset{S_{2} O_{3}^{2 -}}{ \rightarrow }\left(Ag\right)_{2}S_{2}O_{3}\downarrow\text{ (white) }\frac{S_{2} O_{3}^{2 -}}{\text{ excess }}$
$Ag\left(S_{2} O_{3}\right)_{2}^{3 -}$ (Soluable)
$\text{ (4) }\left(AgNO\right)_{3}\overset{\left(NH\right)_{3}}{ \rightarrow }\left(Ag\right)_{2}O\downarrow\text{ (black) }\frac{\left(NH\right)_{3}}{\text{ excess }}\left(\left[Ag \left(\left(NH\right)_{3}\right)_{2}\right]\right)^{+}$
(Soluable)
Hence (2), (3) &(4) are not the answers