Question

Haemoglobin contains 0.33% of iron by weight. The molecular weight of haemoglobin is approximately 67200 g. The number of iron atoms (at. weight of Fe is 56) present in one molecule of haemoglobin are

• A. 1
• B. 6
• C. 4
• D. 2

Answer 1

Answer: (C)

4

Answer 2

$\therefore 0.33$% of iron by weight means 100 g of
haemoglobin has 0.33 g of iron
100 g of haemoglobin contains iron= 0.33 g
$\therefore 67200 g$ of haemoglobin contains iron
$= \frac {0.33 \times 67200}{100} g = 221.76 g$ of Fe
Number of Fe-atoms $\frac {221.76}{56}$
$= 3.96 \approx 4$