Which of the following compounds is considered a saturated hydrocarbon?

A saturated hydrocarbon is a compound that contains only single bonds between carbon atoms and is fully 'saturated' with hydrogen atoms. In the case of octane, which is represented by the formula C₈H₁₈, it consists entirely of carbon and hydrogen atoms bonded together by single bonds, meaning that each carbon atom is bonded to the maximum number of hydrogen atoms possible.

To determine if a hydrocarbon is saturated, you can also refer to the general formula for saturated alkanes, which is CₙH₂ₙ₊₂. For octane, if you apply this formula: with n=8, you would expect to see 2(8)+2 = 18 hydrogen atoms, confirming that octane is indeed saturated.

The other compounds listed are not saturated because they either contain double bonds or are cyclic structures that prevent them from being fully saturated with hydrogen. Ethylene (C₂H₄) and propylene (C₃H₆) contain double bonds between carbon atoms, which reduce the number of hydrogen atoms that can be bonded, indicating they are unsaturated hydrocarbons. Cyclopentene (C₅H₆) is also unsaturated due to the presence of a