Explain whether 1, 3-hexadiene or 1, 5-hexadiene would absorb the longer wavelength of light.

Bromothymol blue is an acid-base indicator that is blue in base and yellow in acid:

$\left(\mathrm{Yellow}\right) \mathrm{HB}\rightleftharpoons {\mathrm{H}}^{+}+{\mathrm{B}}^{-} \left(\mathrm{Blue}\right)$

 Deduce which of the two forms of the indicator has the higher degree of conjugation. Explain it in terms of the wavelength of light absorbed and molecular structure of an organic indicator.