Nessler's reagent is

Which of the following reagents is commonly used to detect the presence of sulfide ions?

Which ion will not be precipitated by aqueous $(NH_4)_2S$?

Identify the metal $M$ and the precipitate $Z$ in the following reaction sequence:
$MSO_4$ $\xrightarrow{NH_4OH} \downarrow X \text{ (white)}$ $\xrightarrow{NH_4OH \text{ (excess)}} Y$ $\xrightarrow{H_2S} \downarrow Z$

$Pb(CH_3COO)_2$ gives a precipitate of which color with $H_2S$?

$A$ mixture of chlorides of $Cu, Cd, Cr$ and $Fe$ was dissolved in water acidified with dil. $HCl$ and $H_2S$ gas was passed. It was filtered,and boiled later adding two drops of $HNO_3$. To this solution $NH_4Cl$ and $NH_4OH$ (or $NaOH$ in excess) were added. The filtrate shall give a test for :-