Three different samples of a salt solution give the following test results: One sample gives a white precipitate with ammonia solution. One sample gives a white precipitate with dilute $NaCl$ solution. One sample gives a black precipitate with $H_2S$. Identify the salt.

The yellow precipitate formed during the chromyl chloride test is chemically

Passing $H_2S$ gas into a mixture of $Mn^{2+}$,$Ni^{2+}$,$Cu^{2+}$ and $Hg^{2+}$ ions in an acidified aqueous solution precipitates

In the group $III$ radicals,in place of $NH_4Cl$,which of the following can be used?

$p$-Amino-$N,N$-dimethylaniline is added to a strongly acidic solution of $X$. The resulting solution is treated with a few drops of aqueous solution of $Y$ to yield blue coloration due to the formation of methylene blue. Treatment of the aqueous solution of $Y$ with the reagent potassium hexacyanoferrate$(II)$ leads to the formation of an intense blue precipitate. The precipitate dissolves on excess addition of the reagent. Similarly,treatment of the solution of $Y$ with the solution of potassium hexacyanoferrate$(III)$ leads to a brown coloration due to the formation of $Z$.
$1.$ The compound $X$ is
$(A)$ $NaNO_3$ $(B)$ $NaCl$ $(C)$ $Na_2SO_4$ $(D)$ $Na_2S$
$2.$ The compound $Y$ is
$(A)$ $MgCl_2$ $(B)$ $FeCl_2$ $(C)$ $FeCl_3$ $(D)$ $ZnCl_2$
$3.$ The compound $Z$ is
$(A)$ $Mg_2[Fe(CN)_6]$ $(B)$ $Fe[Fe(CN)_6]$
$(C)$ $Fe_4[Fe(CN)_6]_3$ $(D)$ $K_2Zn_3[Fe(CN)_6]_2$
Give the answer for questions $1, 2$ and $3$.

$A$ salt '$A$' which gives a green flame with a Bunsen burner,on reaction with dil. $H_2SO_4$ produces gas $(2)$ and white turbidity $(Z)$. The saturated solution of gas $(2)$ on reaction with $H_2S$ gas produces '$Z$'. Then select the $CORRECT$ statement.