RE-NEET 2026 Chemistry Alkenes MCQ Question

Conjugated double bonds occur when alternating single and double bonds are present, allowing for delocalization of electrons. In hepta-1,3-diene, the double bonds are separated by a single bond, forming a conjugated system:

$\text{C=C-C=C}$

This arrangement allows for resonance stabilization.

In contrast, hepta-1,4-diene (A) and hepta-1,5-diene (B) have double bonds that are too far apart to be conjugated, while hepta-1,6-diene (C) has its double bonds at the terminal positions, also lacking conjugation. Thus, only hepta-1,3-diene exhibits the necessary alternating pattern of bonds for conjugation.