The number of iron atoms in a piece of iron weighing 2.8 g is:

To find the number of iron atoms in a piece of iron weighing 2.8 g, follow these steps: Molar mass of iron (Fe) = 56 g/mol. Avogadro's number = 6.022x10^23 atoms/mol. Number of moles of iron = 2.8g / 56g/mol = 0.05 mol. Number of atoms = 0.05 mol x 6.022x10^23 atoms/mol = 3.011x10^22 atoms. Thus, the number of iron atoms in a 2.8 g piece of iron is 3.011x10^22 atoms.