$A$ solution containing a group $IV$ cation gives a precipitate on passing $H_2S$ gas. $A$ solution of this precipitate in dilute $HCl$ produces a white precipitate with $NaOH$ solution and a bluish-white precipitate with basic potassium ferrocyanide. The cation is:

An aqueous solution of a salt $X$ turns blood red on treatment with $CNS^{-}$ and blue on treatment with $K_4[Fe(CN)_6]$. $X$ also gives a positive chromyl chloride test. The salt $X$ is

An aqueous solution containing $FeSO_4$,$Al_2(SO_4)_3$,and chrome alum is treated with $Na_2O_2$ and heated,followed by filtration. The resulting products are:

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 yellow precipitate formed during the chromyl chloride test is chemically

$p$-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 $3$.