Reagents used for the qualitative estimation of $Ni^{+2}$ and $Cu^{+2}$ respectively are:

Lead sulphate is soluble in:

What precipitate is formed when $SnCl_2$ is added to $HgCl_2$?

$Pb^{2+}$,$Cu^{2+}$,$Zn^{2+}$,and $Ni^{2+}$ ions are present in a given acidic solution. On passing hydrogen sulphide gas through this solution,the precipitate formed will contain:

Assign $A, B, C, D$ from the given type of reaction:
$2KCN + Pb(NO_3)_2 \longrightarrow Pb(CN)_2 \downarrow + 2KNO_3$

$A$ light greenish coloured salt was soluble in water. On passing $H_2S$ into the solution,a black precipitate was obtained which dissolved readily in $HCl$. The metal ion present is: