Secondary nitro compounds when react with $HNO_2$ form crystalline solids which on treatment with $NaOH$ give

An aromatic compound "$A$" on treatment with $Zn / NH_4Cl$ and subsequent heating with ammoniacal silver nitrate solution gives a black precipitate. Which functional group does "$A$" contain?

Liebermann's nitroso reaction is used for testing:

Nessler's reagent is

Which of the following does $NOT$ give carbylamine test?

$p-$chloroaniline and anilinium hydrochloride can be distinguished by