Hello!
To find the number of moles that are in the given amount, we need to divide the total number of atoms by Avogadro's number, which is 1 mole is equal to 6.02 x 10^23 atoms.
5.0 x 10^25 / 6.02 x 10^23 ≈ 83.0564
Therefore, there are about 83.06 moles of iron (sigfig: 83 moles).
