When cyclobutylethene (vinylcyclobutane) is treated with dilute H ₂ SO ₄ , the major product formed is:

Step-by-step solution

Protonation of the double bond in cyclobutylethene (vinylcyclobutane) by dilute H ₂ SO ₄ follows Markovnikov's rule, yielding the more stable secondary carbocation, the 1-cyclobutylethyl cation. To relieve the significant ring strain of the four-membered cyclobutane ring, a ring expansion occurs. A C - C bond from the ring migrates to the adjacent carbocation center, expanding the ring to a five-membered cyclopentane ring. This forms the 2-methylcyclopentyl cation, which is still a secondary carbocation. To achieve