When $H_2S$ gas is passed through the $HCl$ containing aqueous solutions of $CuCl_2$,$HgCl_2$,$BiCl_3$ and $CoCl_2$,which does not precipitate out?

$A$ salt on treatment with dil. $HCl$ gives a pungent smelling gas and a yellow precipitate. The salt gives a green flame when tested. The salt solution gives a yellow precipitate with potassium chromate. The salt is:

Sometimes yellow turbidity appears on passing $H_2S$ gas even in the absence of the second group radicals. This happens because

Upon treatment with ammoniacal $H_2S$,the metal ion that precipitates as a sulfide is

When sodium nitroprusside is added to an alkaline solution containing sulfide ions,a ........ is obtained.

To an aqueous solution containing ions such as $Al^{3+}, Zn^{2+}, Ca^{2+}, Fe^{3+}, Ni^{2+}, Ba^{2+}$ and $Cu^{2+}$,concentrated $HCl$ was added,followed by $H_{2}S$. The total number of cations precipitated during this reaction is/are: