The hydrocarbon with molecular formula `C_(5)H`,0 can either a cycloakane or an alkene.
Since the compound does not react with `Cl_(2)` in the dark, therefore it cannot be an alkene but must be a cycloalkane reacts with `Cl_(2)` in the presence of bright sunlight to give a single monochloro compound , `C_(5)H_(9)Cl`, therefore, all the ten hydrogen atoms of the cycloalkanes must be equivalent. Thus, the cycloalkane is cyclopentane.
