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

Identify ions $A$ and $B$,respectively,based on the following reaction scheme:

During the qualitative analysis of a salt with cation $y^{2+}$,the addition of a reagent $(X)$ to an alkaline solution of the salt gives a bright red precipitate. The reagent $(X)$ and the cation $(y^{2+})$ present are respectively .... .

$A$ white crystalline substance dissolves in water. On passing $H_2S$ in this solution,a black precipitate is obtained. The black precipitate dissolves completely in hot $HNO_3$. On adding a few drops of conc. $H_2SO_4$ a white precipitate is obtained. This precipitate is that of:

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

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