Molecular formula tells us the actual numbers of each type of atom in a molecule.

• A. The simplest ratio of atoms
• B. The mass of a molecule
• C. The actual numbers of each type of atom in a molecule
• D. The total charge of a molecule

Answer: (C)

The main idea here is understanding what a molecular formula tells you about a compound. A molecular formula lists the exact numbers of each type of atom in one molecule, not just a simple ratio. That’s why it’s the best description: it shows the real counts, such as H2O having two hydrogens and one oxygen, or glucose having C6H12O6.

This differs from the simplest ratio used in the empirical formula, which reduces the atom counts to the smallest whole-number ratio (for glucose, CH2O is the empirical formula, while the molecular formula is C6H12O6). The molecular formula also doesn’t directly give the molecule’s mass, which you would compute by adding up the atomic masses, nor does it specify the molecule’s total charge.