Answer: Gaseous
Explanation: Straight Chain hydrocarbon having three carbon atoms is known as Propane. It molecular formula is
CH_{3}CH_{2}CH_{3}
Inter molecular forces of attraction that is London Dispersion Forces existing between its molecules are weaker that is why the propane is gaseous in nature at room temperature.
It is also used in LPG. Boiling Point of propane is -42° C.