Avogadro's number is used to determine the number of subatomic particles in an atom.

the answer is false because In chemistry and physics, Avogadro's number usually refers to a quantity of atoms

"Avogadro's number is a proportion that relates molar mass on an atomic scale to physical mass on a human scale. Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is equal to 6.022*1023 mol-1 and is expressed as the symbol NA."