Question

Which material is diamagnetic?

• A. Iron
• B. Copper
• C. Nickel
• D. Cobalt

Hint:

Most noble metals and covalent/ionic solids like Copper (Cu), Gold (Au), Silver (Ag), and Water ($H_2O$) are diamagnetic.
Fe, Co, and Ni are always ferromagnetic at room temperature.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the diamagnetic material among the given choices.
Diamagnetism is a property of materials that are weakly repelled by an external magnetic field.

Step 2: Key Formula or Approach:
- Ferromagnetic materials: Have strong, permanent magnetic alignment (e.g., Fe, Co, Ni).
- Diamagnetic materials: Have fully filled electronic shells with no unpaired electrons, resulting in a net magnetic moment of zero in the absence of an external field.

Step 3: Detailed Explanation:

• Iron (Fe), Cobalt (Co), and Nickel (Ni) are the classic transition metals that exhibit ferromagnetic behavior at room temperature due to their partially filled d-shells and strong exchange interactions.

• Copper (Cu) has the electronic configuration $[Ar] 3d^{10} 4s^1$. When metallic bonds form in bulk copper, the $3d$ subshell remains completely filled. The electronic states are paired, leading to a weak diamagnetic response when subjected to an external magnetic field.

• Consequently, copper is repelled by magnetic fields and has a small, negative magnetic susceptibility.

Step 4: Final Answer: The diamagnetic material is Copper.