Question

The plot showing the magnetic behavior of oxy- (solid line) and deoxy-haemoglobin (dashed line) is 

 

• A. (A)
• B. (B)
• C. (C)
• D. (D)

Hint:

Oxy-hemoglobin is paramagnetic due to the binding of oxygen, while deoxy-hemoglobin is diamagnetic due to its iron in the low-spin state.

Answer 1

The Correct Option is A

To solve this question, we need to understand the magnetic properties of oxy-haemoglobin and deoxy-haemoglobin.

• Oxy-haemoglobin: It is diamagnetic because oxygen bonding to iron in hemoglobin results in the pairing of all d-electrons. This results in zero unpaired electrons, eliminating magnetic properties.
• Deoxy-haemoglobin: It is paramagnetic because the absence of oxygen leaves some unpaired electrons on iron, imparting magnetic properties.

The plot of magnetic susceptibility \(\chi_M T\) versus temperature \(T\) helps to establish these differences. In diagrams:

• Diamagnetic materials show no change in \(\chi_M T\) with temperature. This is why the line for oxy-haemoglobin (solid line) remains flat.
• Paramagnetic materials exhibit a temperature-independent line above zero, which can be seen for deoxy-haemoglobin (dashed line).

From the given options, we identify the plot as follows:

In option (A), the plot clearly shows:

• The solid line at \(\chi_M T = 0\), consistent with the diamagnetic nature of oxy-haemoglobin.
• The dashed line remaining above zero, reflecting the paramagnetic characteristic of deoxy-haemoglobin.

Therefore, the correct answer is option (A).