Final answer:
The correct units for formula mass (molecular mass) are atomic mass units (amu) or grams per mole (g/mol).
Step-by-step explanation:
The correct units for formula mass, also known as molecular mass, are atomic mass units (amu) or grams per mole (g/mol).
The formula mass of a substance is the sum of the average atomic masses of each atom represented in the chemical formula. It is expressed in atomic mass units (amu). The formula mass of a covalent compound is also called the molecular mass. For example, one molecule of H₂O has a formula mass of approximately 18 amu, and one mole of H₂O molecules has a formula mass of approximately 18 g/mol.