Question

Which of the following is not a chromophore

• A. $- N = N -$
• B. $- NO$
• C. $- NO_{2}$
• D. $- NH_{2}$

Answer 1

Answer: (D)

$- NH_{2}$

Answer 2

A dye molecule is made up of two different part (i) Chromophore (ii) Auxochrome. The groups which produce colour in a compound i.e., chromophores are usual unsaturated groups like nitro, nitroso, azo, azoxy, carbonyl and olefinic bonds Auxochrome are usually acidic / basic functional group like $- OH,$ $- COOH,$ $- SO_{3}H,$ $- NH_{2},$ $- NHR,$ $- NR_{2}$.

A compound containing only a chromophore may be coloured material but not a dye. For example azo benzene is red coloured but not a dye. Where as para amino azobenzene (aniline yellow) is a dye.