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

In the analysis of Group-$II$ basic radicals,$H_2S$ gas is passed in the presence of dilute $HCl$ because...

On treating a solid salt $A$ with dil. $H_2SO_4$ and warming,reddish-brown fumes of gas $B$ are evolved. Addition of $C$ to the salt solution of $A$ followed by freshly prepared starch solution and acidification with acetic acid produces a blue colour. $C$ may contain:

$A$ colourless crystalline salt $X$ is soluble in dilute $HCl$. On adding $NaOH$ solution,it gives a white precipitate which is insoluble in excess of $NaOH$. $X$ is

Match List-$I$ with List-$II$.

$LIST$-$I$ (Precipitating reagent and conditions)	$LIST$-$II$ (Cation)
$A$. $NH_4Cl + NH_4OH$	$I$. $Mn^{2+}$
$B$. $NH_4OH + (NH_4)_2CO_3$	$II$. $Pb^{2+}$
$C$. $NH_4OH + NH_4Cl + H_2S$ gas	$III$. $Al^{3+}$
$D$. Dilute $HCl$	$IV$. $Sr^{2+}$

Choose the correct answer from the options given below:

Find the compound $A$ from the following reaction sequences:
$A$ $\xrightarrow{\text{aqua-regia}} B$ $\xrightarrow[(2) CH_3COOH]{(1) KNO_2 \mid NH_4OH} \text{yellow ppt}$