Question

The haemoglobin of most mammals contains approximately $0.33\%$ of iron by mass. The molecular mass of haemoglobin is $67200$. The number of iron atoms in each molecule of haemoglobin is:

• A. $3$
• B. $4$
• C. $2$
• D. $6$

Answer 1

The correct option is B $4$

Percentage of $Fe=0.33$

Molecular weight of haemoglobin = 67200

Weight of $Fe$ present$=\left(\frac{0.33}{100}\right)\times 67200=221.8$

One Fe weights $55.8$g

Therefore, number of Fe atoms = $\frac{221.8}{55.8}=4$

Hence, 4 atoms of iron are present in one molecule of haemoglobin.

Therefore, option $B$ is correct.