How many atoms of Fe are in 45.00 grams of Fe?

4.852*10^23

Explanation:

Use dimensional analysis.

First turn grams to moles using the molar mass of Fe (you can't convert to atoms from grams).

Then turn moles into atoms using Avogadro's constant.

45g Fe/55.85 g/mol Fe*6.022*10^23 atoms Fe