Which compound is a member of the same homologous series as c3h8?

C3H8 is called propane. It belongs to alkane family, which have the general formula CnH2n+2.
In the alkanes, the number of hydrogen atoms is double than the number of carbon atoms along with two additional carbon atoms.

So, to the same homologous series, the other members are the other alkanes example -
1) CH4 (methane)
2) C2H6 (ethane)
3) C4H10 (butane)
4) C5H10 (pentane)

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)