Benzamide and benzylamine can be distinguished by

$A$ $\xrightarrow{PhSO_2Cl} B$ $\xrightarrow{KOH} C$ $\xrightarrow{C_2H_5I} D$
$C$ is water soluble.
Correct structures of $A$ and $D$ are:

The test that distinguishes primary amines from other amines is

Liebermann's nitroso reaction is used for testing:

An aromatic compound $A$ reacts with $Zn/NH_4Cl$,and the filtrate is then added to an ammoniacal silver nitrate solution,resulting in a black precipitate. Which group does compound $A$ contain?

Explain the isocyanide test.