Final answer:
Allylic radicals are more stable than primary, secondary, tertiary, or vinyl radicals because of resonance stabilization. This is true because the unpaired electron in an allylic radical can delocalize over adjacent π bonds, increasing their overall stability.
Step-by-step explanation:
To answer the question regarding the stability of different types of radicals: Allylic radicals are indeed more stable than primary, secondary, tertiary, or vinyl radicals, and thus the correct answer to the question is True. The stability of allylic radicals is attributed to the ability of the unpaired electron to be delocalized over the neighboring π bonds. This delocalization leads to resonance stabilization, which makes allylic radicals relatively more stable than other radicals like primary, secondary, or tertiary ones, which lack this stabilization effect.
It's important to understand that the stability of radicals typically increases in this order: primary (RCH₂) < secondary (R₂CH) < tertiary (R₃C). Allylic radicals, however, have a unique stability due to the ability of their unpaired electron to resonate across adjacent multiple bonds, enhancing their stability beyond that of even tertiary radicals. This is why the stability of allylic radicals is often compared to that of tertiary radicals in organic chemistry discussions.