Assertion: Cyclopentadienyl anion is much more stable than allyl anion. Reason: Cyclopentadienyl anion is aromatic in character.

The cyclopentadienyl anion is shown below whose resonance structure is shown below- Also, 4 2 electrons 6 4n 6 2 4n 4 n 1 >> >> Where as in allyl anion 2 2 2 2 Allyl Anion CH CH CH H C CHCH Here we can see that cyclopentadienyl anion is stable because it is aromatic and allyl anion has only two resonance structures. Thus, the correct option is (a) Both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.