2.047 × 10^24 atoms
In this case we are given 3.4 moles of Iron.
we are required to find the number of atoms in 3.4 moles.
Therefore, since 1 mole of Fe contains 6.022 × 10^23 atoms.
Then, 3.4 mole will contain;
= 3.4 moles × 6.022 × 10^23 atoms/mole
= 2.047 × 10^24 atoms
Thus, 3.4 moles of Iron contains 2.047 × 10^24 atoms