Aqueous solution of $FeSO_4$ does not produce a precipitate with:

Which of the following pairs cannot be distinguished by passing $H_2S$ gas?

$A$ 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:

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

$Pb(CH_3COO)_2$ gives a precipitate of which color with $H_2S$?

Sodium nitroprusside when reacts with a solution of $Na_2S$,produces: