how many atoms of iron are in 2.8 moles of... FeWO4 Fe3O4 FeS2 Fe2O3?

1 mole of Fe contains 6.022 × 10²³ Fe atoms.

1 mole of FeWO₄ contains 1 mole of Fe atoms.
No. of Fe atoms in 2.8 moles of FeWO₄ = 2.8 × (6.022 × 10²³) = 1.69 × 10²⁴

1 mole of Fe₃O₄ contains 3 mole of Fe atoms.
No. of Fe atoms in 2.8 moles of Fe₃O₄ = 2.8 × (6.022 × 10²³) × 3 = 5.06 × 10²⁴

1 mole of FeS₂ contains 1 mole of Fe atoms.
No. of Fe atoms in 2.8 moles of FeS₂ = 2.8 × (6.02 × 10²³) = 1.69 × 10²⁴

1 mole of Fe₂O₃ contains 2 mole of Fe atoms.
No. of Fe atoms in 2.8 moles of Fe₂O₃ = 2.8 × (6.02 × 10²³) × 2 = 3.37 × 10²⁴