Amines practice · Easy

Option B (nitrito) is correct because nitrito ($\mathrm{NO_2^-}$) can coordinate through either the nitrogen or one of the oxygen atoms, making it an ambidentate ligand.

Option D (In acidic medium by first converting it into acetanilide before nitration) is correct because aniline is first converted to acetanilide to protect the amino group from oxidation and to control the reaction.

Option C (Primary amine) is correct because primary amines react with chloroform and a base to form isocyanides, which have a foul smell and indicate a positive carbylamine test.

Option A ($\mathrm{C}{\mathrm{H}_3}\mathrm{N}{\mathrm{H}_2}$) is correct because primary amines react with Hinsberg reagent to form N-substituted sulfonamides, which are soluble in alkali.

Option D ((C2H5)3N) is correct because tertiary amines lack a hydrogen atom directly attached to the nitrogen, preventing them from reacting with benzenesulfonyl chloride.

Option C (Almost neutral) is correct because an aqueous solution of urea is nearly neutral, although it can act as a weak monoacid-base.

The correct answer is A (Ar-F) because the reaction sequence involves the formation of an aryl diazonium tetrafluoroborate salt, followed by thermal decomposition to yield an aryl fluoride.

Option A is correct because the lone pair of electrons on the nitrogen atom in aniline is delocalized into the benzene ring through resonance, making it less available for protonation compared to ethylamine.

Option C (${C_6}{H_5}S{O_2}Cl$) is correct because Hinsberg’s reagent is benzene sulphonyl chloride, used to distinguish between primary, secondary, and tertiary amines.

Option D (${\mathrm{C}_6}{\mathrm{H}_5}\mathrm{C}{\mathrm{H}_2}\mathrm{N}{\mathrm{H}_2}$) is the most basic because the lone pair on the nitrogen is not delocalized into the benzene ring, making it more available for protonation.

Option B (Aromatic aldehydes) is correct because Schiff's bases are formed by the condensation reaction between primary amines (like aniline) and aldehydes (especially aromatic aldehydes).