halogenoalkane: add NaOH (aq) and warm, acidify with HNO₃, add AgNO₃ (aq); precipitate forms:Cl⁻ is white, Br⁻ is cream, I⁻ is yellow
add ammonia solution to determine precipitate: AgCl dissolves in dilute ammonia solution, AgBr dissolves in concentrated dilute ammonia, AgI does not dissolve in ammonia solution