Question

Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately $67200\text{amu}$. The number of iron atoms (Atomic weight of $Fe$ is 56) present in one molecule of haemoglobin is:

• A. 4
• B. 6
• C. 3
• D. 2

Answer 1

The correct option is A 4

Mass of 1 mol of haemoglobin is $67200\text{g}$
Mass of iron in 1 mol of haemoglobin $=\frac{0.334}{100}\times 67200=224.448\text{g}$
Moles of iron in 1 mol of haemoglobin $=\frac{224.448}{56}=4$
Now 1 mol of haemoglobin contains 4 mol of iron atoms.
So, 1 molecule of haemoglobin contains 4 atoms of iron.