Mark the compound which turns black with $NH_4OH$.

$A$ 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

Addition of sodium thiosulphate solution to a solution of silver nitrate gives $X$ as a white precipitate, which is insoluble in water but soluble in excess thiosulphate solution to give $Y$. On boiling in water, $Y$ gives $Z$. $X$, $Y$, and $Z$ respectively are:

Which sulfide is soluble in $(NH_4)_2CO_3$?

Which ion is precipitated by the reagent $NH_4Cl$ and aqueous $NH_3$?

Consider the following reaction scheme: $D(\text{White ppt}) \xleftarrow{Na_2CO_3} A \xrightarrow[\text{in acetic acid}]{K_2CrO_4} B(\text{Yellow ppt})$ and $A \xrightarrow{dil.\ H_2SO_4} C(\text{White ppt})$. If $A$ is a metallic salt,then the white precipitate $D$ must be: