$A$ pink coloured salt turns blue on heating. The presence of which cation is most likely?

$A$ solution of a metal ion,when treated with $KI$,gives a red precipitate which dissolves in excess $KI$ to give a colourless solution. Moreover,the solution of the metal ion,on treatment with a solution of cobalt$(II)$ thiocyanate,gives rise to a deep blue crystalline precipitate. The metal ion 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:

The reagent used for the identification of $Ni^{2+}$ ions is .....

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$AlCl_3 + Na_3PO_4 \longrightarrow AlPO_4 \downarrow$

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.