Which ion will not be precipitated by aqueous $(NH_4)_2S$?

The solution of $BiCl_{3}$ in dil. $HCl$ when diluted with water,forms a white precipitate which is:

$A$ reagent used to test the presence of $Fe^{2+}$ ion is

Which compound does not dissolve in hot dilute $HNO_3$?

$A$ 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:

Which reagents are used for the identification of Group $IV$ cations?