When calomel reacts with a solution of $NH_4OH$,which compound is formed?

$A$ white crystalline substance dissolves in water. On passing $H_2S$ in this solution,a black precipitate is obtained. The black precipitate dissolves completely in hot $HNO_3$. On adding a few drops of conc. $H_2SO_4$ a white precipitate is obtained. This precipitate is that of:

$A$ solution contains $Cl^{-}$,$I^{-}$,and $SO_{4}^{2-}$ ions. Which of the following ions is capable of precipitating all of the above when added to this solution?

The distinguishing reagent between silver and lead salts is:

$A$ salt '$A$' which gives a green flame with a Bunsen burner,on reaction with dil. $H_2SO_4$ produces gas $(2)$ and white turbidity $(Z)$. The saturated solution of gas $(2)$ on reaction with $H_2S$ gas produces '$Z$'. Then select the $CORRECT$ statement.

When $H_2S$ gas is passed through an $HCl$ solution containing $CuCl_2, HgCl_2, BiCl_3$,and $CoCl_2$,which of the following will not precipitate?