What is the total number of strictly cyclic, structural isomer ring systems (neglecting any stereois — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

$C_5H_{10}$ possesses a DU of 1, allowing for one ring. The structural cyclic possibilities are: cyclopentane (5-ring), methylcyclobutane (4-ring), 1,1-dimethylcyclopropane (3-ring), 1,2-dimethylcyclopropane (3-ring), and ethylcyclopropane (3-ring). This results in exactly 5 distinct cyclic structural frameworks.