Chemistry - GOC Question with Solution | TestHub

Conjugation gives resonance stabilisation, so the conjugated hexa-2,4-diene (III) is the most stable. Of the two isolated dienes, (I) has an internal disubstituted $\mathrm{C}=\mathrm{C}$, and (II) has two terminal monosubstituted $\mathrm{C}=\mathrm{C}$ bonds, so (I) is more stable than (II). Order : III $>$ I $>$ II.