Which sulphide is soluble in $(NH_4)_2CO_3$?

Which compound is used to distinguish between $Fe^{2+}$ and $Fe^{3+}$ ions?

$X_2S_n + H_2O \to X(OH)_n \downarrow + Y \uparrow (Gas) \xrightarrow{Pb(CH_3COO)_2} Z \downarrow (Black \ ppt.)$
Then $(X)$ cation can not be

Which of the following gives a black precipitate when $H_2S$ gas is passed through its solution?

$A$ 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:

Of the following sulphides,which one is insoluble in dilute acids but soluble in alkalies?