$A$ reagent used to test the presence of $Fe^{2+}$ ion is

Three separate samples of a solution of a single salt gave these test results: one formed a white precipitate with excess ammonia solution,one formed a white precipitate with dilute $NaCl$ solution,and one formed a black precipitate with $H_2S$. The salt could be:

On passing $H_2S$ gas,a black precipitate of $II$ group is obtained. The mixture may not contain:

When calomel reacts with a solution of $NH_4OH$,which compound is formed?

Which of the following compounds is not soluble in hot dilute $HNO_3$?

$A$ 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 :-