Solution:

The mechanism of acid hydrolysis was discussed in Ester #1 of this module. The decarboxylation of β-ketoacids was addressed in Ester #3. It is critical for the β-ketoacid upon loss of CO₂ to form an enol. From another perspective there must be orbital overlap between the π-bond of the ketone and the σ-bond attached to the carboxyl group. Structure 5 has strong overlap of the red orbitals with the axial carboxylate group. Loss of CO₂ leads to enol 6 which tautomerizes to cyclohexanone. Structure 7 has poor ovelap between the red and blue orbitals. Its enol would afford trans cylohexene enol 8 (in red), a violation of Bredt's Rule.