(N/A) Benzene diazonium chloride is prepared by the reaction of aniline with nitrous acid at $273-278 \ K$.
Nitrous acid is produced in the reaction mixture by the reaction of sodium nitrite with hydrochloric acid.
The conversion of primary aromatic amines into diazonium salts is known as diazotisation.
Due to its inherent instability,the diazonium salt is not generally stored and is used immediately after its preparation.
Benzene diazonium chloride is a colourless crystalline solid that is readily soluble in water.
It is stable in cold conditions but reacts with water when warmed and decomposes easily in the dry state.