Answer: a hydrocarbon
Explanation:
1. Functional group is a specific group of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.
2. A halogen is the name of group 17 elements containing fluorine, chlorine, bromine, iodine and astatine.
3. A hydrocarbon is a compound containing carbon and hydrogen. Example: alkanes, alkenes and alkynes.
Propane is an alkane with molecular formula [tex]C_3H_8[/tex].
4. An ester is a functional group [tex]-O=C-OR[/tex].
