When $H_2S$ gas is passed through a solution,it reacts to form a white precipitate. Which ion is present in the solution?

$A$ (Orange color compound) $\xrightarrow{(B) + \text{conc. } H_2SO_4}$ $C$ (Red gas) $\xrightarrow{NaOH + AgNO_3}$ $D$ (Red ppt.) $\xrightarrow{\text{NH}_3 \text{ solution}}$ Yellow solution.
$B$ $\xrightarrow[\Delta]{NaOH}$ $F \uparrow$ (Gives white fumes with $HCl$).
Identify $B$ and $F$ respectively :-

To a solution of a substance,gradual addition of ammonium hydroxide results in a black precipitate which does not dissolve in excess of $NH_4OH$. However,when $HCl$ is added to the original solution,a white precipitate is formed. The solution contained

The reagent used in the qualitative analysis of the $IV^{th}$ group basic radicals is:

Which of the following is an incorrect match for the precipitate (ppt) and its color?

In qualitative analysis,in order to detect $II$ group basic radicals,$H_2S$ gas is passed in the presence of dilute $HCl$ to: