Final answer:
The location of the functional group in a molecule is indicated by a number placed before the functional group's name.
Step-by-step explanation:
The location of the functional group in a molecule is indicated by a number placed before the functional group's name. This number represents the position of the carbon atom where the functional group is attached.
For example, in the compound 2-propanol, the functional group is an alcohol (-OH) and it is attached to the second carbon atom in the parent chain. The number 2 in the name indicates the location of the functional group.
Similarly, in the compound 3-bromo-1-butene, the functional group is a halogen (bromine - Br) and it is attached to the third carbon atom in the parent chain. The number 3 in the name indicates the location of the functional group.