Chemistry Industrial Chemistry PMDC Conceptual Practice
PMDC Verified Question 17 of 41
Which functional structural group is primarily responsible for imparting color to an organic dye molecule?
A
Chromophore
B
Auxochrome
C
Solubilizing group
D
Aliphatic spacer
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Chromophore
Concept:

A chromophore is the essential light-absorbing electronic system of a dye molecule that enables selective absorption of visible wavelengths.

Formula / Reaction:

Qualitative concept / No formula required.

Solution:

  • Without a chromophoric group (such as \(-\text{N}=\text{N}-\), \(-\text{NO}_2\), or quinoid systems), an organic compound appears colorless in visible light.


Why other options are incorrect:

  • Auxochrome: Modifies color depth and intensity (bathochromic/hyperchromic shift) but cannot produce color independently.


  • Solubilizing group: Grants water solubility (e.g., \(-\text{SO}_3\text{Na}\)).


  • Aliphatic spacer: Saturated carbon chains that interrupt conjugation and reduce color intensity.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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