Question

Haemoglobin contains $0.334\%$ of iron by weight. The molecular weight of haemoglobin is approximately 672000 g. The number of iron atoms (Atomic weight of $Fe$ is $56gmo{l}^{-1}$) present in one molecule of haemoglobin is:

• A. 1
• B. 2
• C. 4
• D. 6

Answer 1

The correct option is C 4

100 g of haemoglobin contains $=0.334\text{g Fe}$
$\therefore$ 67200 g of haemoglobin contains
$=\frac{0.334\times 67200}{100}=224.45\text{g of Fe}$
Now,
$\therefore$ 56 g of iron = 1 mole of $Fe$ atoms
$\therefore$ 224.45 g iron $=\frac{1\times 224.45}{56}$
$\approx$ 4 moles of $Fe$ atoms.
$\therefore$ 1 molecule of Haemoglobin = 4 $Fe$ atoms.