Identify the paramagnetic substance

Options

A. Iron
B. Aluminium
C. Nickel
D. Hudrogen

Answer

To identify the paramagnetic substance from the given options (iron, aluminum, nickel, and hydrogen), we need to understand the concept of magnetic susceptibility and the classification of materials based on their magnetic properties.

### Step-by-Step Solution:

1. **Understanding Magnetic Susceptibility**:
- Magnetic susceptibility (\( \chi_m \)) is a measure of how much a material will become magnetized in an applied magnetic field.
- Materials can be classified as diamagnetic, paramagnetic, or ferromagnetic based on their susceptibility values.

2. **Classifying the Given Substances**:
- **Iron (Fe)**:
- Iron has a very high positive magnetic susceptibility (\( \chi_m \)), indicating that it is a ferromagnetic material.
- Since its susceptibility is much greater than zero, it does not qualify as paramagnetic.

- **Nickel (Ni)**:
- Nickel also has a high positive magnetic susceptibility, but it is lower than that of iron.
- Like iron, nickel is classified as a ferromagnetic material due to its large positive susceptibility.

- **Aluminum (Al)**:
- Aluminum has a small positive magnetic susceptibility.
- Because its susceptibility is positive but small, aluminum is classified as a paramagnetic substance.

- **Hydrogen (H)**:
- Hydrogen is known to be a diamagnetic substance, meaning it has a negative susceptibility.

3. **Conclusion**:
- Among the options provided, aluminum is the only substance that is classified as paramagnetic due to its small positive magnetic susceptibility.

### Final Answer:
The paramagnetic substance from the given options is **aluminum**.

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