Explain the reaction of nitrous acid with amines.

(N/A) Three classes of amines react differently with nitrous acid $(HNO_2)$,which is prepared in situ from a mineral acid and sodium nitrite $(NaNO_2)$.
$(i)$ Reaction of primary aliphatic amines with nitrous acid: Primary aliphatic amines react with nitrous acid to form aliphatic diazonium salts,which are unstable and decompose to liberate nitrogen gas $(N_2)$ quantitatively,forming alcohols $(R-OH)$.
$(ii)$ Reaction of primary aromatic amines with nitrous acid: Aromatic amines react with nitrous acid at low temperatures $(273-278 \ K)$ to form stable diazonium salts,which are important intermediates for the synthesis of various aromatic compounds.
$(iii)$ Secondary and tertiary amines react differently with $HNO_2$. Secondary amines form $N$-nitrosoamines (yellow oily liquids),while tertiary amines form salts that are soluble in water.