Which ion will form a precipitate with both $HCl$ and $H_2S$?

$A$ metal nitrate reacts with $KI$ to give a black precipitate which on addition of excess of $KI$ converts into an orange-colored solution. The cation of the metal nitrate is

$A$ metal salt solution forms a yellow precipitate with potassium chromate in acetic acid,a white precipitate with dilute $H_2SO_4$,but gives no precipitate with $NaCl$. The metal salt solution will consist of:

Which compound gives a black color with $NH_4OH$?

In the analysis of basic radicals,the group reagent $H_2S$ gas is generally used in which groups?

Which of the following compounds can produce Rinmann's green with $Co(NO_3)_2$ solution?