An example of a diamagnetic substance is

Options

A. aluminium copper
B. copper
C. iron
D. nickel

Answer

To determine an example of a diamagnetic substance from the given options (A: Aluminum, B: Copper, C: Iron, D: Nickel), we will analyze the magnetic susceptibility of each substance.

### Step-by-Step Solution:

1. **Understanding Diamagnetism**:
- Diamagnetic substances are characterized by having a negative magnetic susceptibility (χ < 0). This means they are repelled by a magnetic field.

2. **Analyzing Aluminum (Option A)**:
- The magnetic susceptibility of aluminum (χ_Al) is greater than 0, indicating that it is paramagnetic, not diamagnetic.

3. **Analyzing Copper (Option B)**:
- The magnetic susceptibility of copper (χ_Cu) is less than 0, which means it is a diamagnetic material. This is a strong candidate for our answer.

4. **Analyzing Iron (Option C)**:
- The magnetic susceptibility of iron (χ_Fe) is significantly greater than 0, indicating that it is ferromagnetic. Therefore, it cannot be a diamagnetic substance.

5. **Analyzing Nickel (Option D)**:
- The magnetic susceptibility of nickel (χ_Ni) is also greater than 0, classifying it as a ferromagnetic substance, similar to iron.

6. **Conclusion**:
- After analyzing all options, we find that only copper has a negative magnetic susceptibility, making it the only diamagnetic substance among the options provided.

### Final Answer:
The example of a diamagnetic substance is **B: Copper**.

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