Haemoglobin contains 0.33% of iron by weight. Molecular weight of haemoglobin

Haemoglobin contains 0.33% of iron by weight. Molecular weight of haemoglobin is approximately 67200. How many iron atoms are present in molecule of Haemoglobin

Percentage of Fe = 0.33% molecular weight of haemoglobin
Weight of Fe present = (0.33/100) × 67200 = 221.8
one Fe weighs 55.8 g
Therefore, 221.8/55.8 = 4
Hence, 4 atoms of iron are present in one molecule of haemoglobin.