Concept:According to Witt's color theory, the color of an organic dye arises from an unsaturated light-absorbing structural unit known as a chromophore.
Formula / Reaction:$$\Delta E = h\nu = \frac{hc}{\lambda} \quad (\text{Absorption in } 400\text{--}700\text{ nm range})$$
Solution:- Chromophores possess conjugated \(\pi\)-electron systems (e.g., \(-\text{N}=\text{N}-\), \(>\text{C}=\text{O}\), \(-\text{NO}_2\)) where electronic energy gaps (\(\Delta E\)) correspond to visible photons.
Why other options are incorrect:- Auxochrome: An electron-donating or withdrawing group (e.g., \(-\text{OH}\), \(-\text{NH}_2\)) that intensifies color and shifts \(\lambda_{\text{max}}\), but cannot generate color alone.
- Mordant: An inorganic polyvalent metal salt used to fix dyes to fibers.
- Substrate: The textile fiber or material being dyed.
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