The compound C3H7OH has two possible names, depending on the arrangement of the atoms:

1-Propanol: If the hydroxyl group (OH) is attached to the first carbon in the three-carbon chain, the name is 1-propanol.

2-Propanol: If the hydroxyl group (OH) is attached to the second carbon in the three-carbon chain, the name is 2-propanol.

You need to know the structure of the molecule to determine which name is correct.