Nessler's reagent is

Sodium nitroprusside when reacts with a solution of $Na_2S$,produces:

The group reagent for analytical group $IV$ is:

Identify $A$,$B$ and $C$ in the given reaction sequence.

$A$ 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:

$A$ salt with a few drops of conc. $HCl$ gives an apple green colour in a flame test. The group precipitate of the salt is dissolved in acetic acid and treated with $K_{2}CrO_{4}$ to give a yellow precipitate. When the sodium carbonate extract of the salt solution is heated with conc. $HNO_{3}$ and ammonium molybdate, it results in a canary yellow precipitate. The cation and anion present in the salt are respectively,