Question

The metal present in blood is
A. $Al$
B. $Hg$
C. $Cu$
D. $Fe$

Answer 1

Hint: Haemoglobin is the main constituent of our blood. Thus the metal present in haemoglobin is the only metal present in our blood. Haemoglobin helps in transporting oxygen to our blood with help of these metals.

Complete Step by Step Solution:
Haemoglobin is the major constituent of our blood. Haemoglobin contains the heme unit. It contains the only metal atom iron or $Fe$ . In haemoglobin the iron atom exists in $+2$ oxidation state. Haemoglobin contains a porphyrin ring where the iron atom is connected with the porphyrin ring through nitrogen atoms of the porphyrin ring.

Oxygen can combine with haemoglobin in a bent fashion called as oxy haemoglobin and increases the oxidation state of iron to$+3$. The combination of oxygen makes haemoglobin pure and supplies the oxygen to our blood. Due to the presence of iron, the colour of our blood is red. Thus our blood contains iron metal.

Again copper metal is present in hemocyanin.
A small amount of aluminium is present in our body. $Hg$ is harmful for us.
Thus the correct option is D.

Note: Haemoglobin is essential for oxygen transport in our blood. The iron atom remains in $+2$ oxidation state and exists as high spin iron. When iron connects with oxygen atoms in a bent fashion the oxidation state of iron changes to $+3$ and iron becomes low spin.