What is formed when calomel $(Hg_2Cl_2)$ reacts with $NH_4OH$?

Three different samples of a salt solution give the following test results: One sample gives a white precipitate with ammonia solution. One sample gives a white precipitate with dilute $NaCl$ solution. One sample gives a black precipitate with $H_2S$. Identify the salt.

Which compound gives a black color with $NH_4OH$?

Sodium carbonate cannot be used in place of ammonium carbonate for the precipitation of the fifth group radicals because

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Fe(OH)_3 \downarrow + NaOH(\text{excess}) \longrightarrow \text{No reaction}$

In the analysis of Group-$II$ basic radicals,$H_2S$ gas is passed in the presence of dilute $HCl$ because...