Question

Which among the following elements does NOT exhibit ferromagnetic properties?

• A. Cr
• B. Fe
• C. Co
• D. Ni

Hint:

Ferromagnetic materials (like Fe, Co, Ni) have strongly aligned magnetic moments, leading to permanent magnetism. Antiferromagnetic materials (like Cr) have opposing magnetic moments that cancel out, resulting in no net magnetism.

Answer 1

The Correct Option is A

Step 1: Understanding ferromagnetism Ferromagnetism is a phenomenon in which the magnetic moments of atoms in a material align parallel to each other due to strong exchange interactions. As a result:

• The material exhibits strong magnetization in the presence of an external magnetic field.
• It retains magnetization even after the external field is removed (hysteresis).

This behavior arises due to the presence of \textit{unpaired electrons} and cooperative alignment of spins in domains. Common ferromagnetic elements include: \[ \text{Fe, Co, Ni} \]
Step 2: Comparison with other magnetic behaviors

• Ferromagnetic: Parallel alignment of magnetic moments $\Rightarrow$ strong magnetization
• Antiferromagnetic: Equal and opposite alignment $\Rightarrow$ net magnetization $= 0$
• Paramagnetic: Random alignment, weak attraction in magnetic field
• Diamagnetic: No unpaired electrons, weak repulsion

Step 3: Analysis of given elements

• A. Chromium (Cr): Chromium exhibits \textit{antiferromagnetism}. In this case, adjacent atomic magnetic moments align in opposite directions, cancelling each other. Hence, no net magnetization is observed.
• B. Iron (Fe): Iron has multiple unpaired electrons and strong exchange interactions. It shows domain formation and strong ferromagnetic behavior.
• C. Cobalt (Co): Cobalt also exhibits ferromagnetism due to unpaired electrons and aligned domains.
• D. Nickel (Ni): Nickel is ferromagnetic, though weaker than iron, due to fewer unpaired electrons.

Step 4: Key reasoning Only those elements in which magnetic domains align in the same direction exhibit ferromagnetism. Chromium, due to its antiferromagnetic nature, does not show this behavior.
Step 5: Conclusion \[ \boxed{\text{Chromium (Cr) does not exhibit ferromagnetism \]