He contains the largest number; Fe contains the smallest number.
One mole of anything contains the same number (Avogadro’s number) of particles as one mole of anything else, so all we must do is decide which sample contains the most moles.
Moles = mass/molar mass or n = m/MM
Thus,
No. of atoms ∝ n ∝ 1/MM.
The element with the smallest molar mass, He, has the largest number of atoms.
The element with the largest molar mass, Fe, has the smallest number of atoms.
