Explanation:

The number of moles can be calculated by dividing the number of atoms by Avogadro's number, which is 6.022 x 10^23 atoms/mole.

Therefore, the number of moles in 2.16 x 10^24 atoms of iron is:

$$2.16 \times 10^{24} \ atoms \ Fe \times \frac{1 \ mole \ Fe}{6.022 \times 10^{23} \ atoms \ Fe} = 36.0 \ moles \ Fe$$

So, there are 36.0 moles of iron in 2.16 x 10^24 atoms of iron.