The susceptibility of a perfectly diamagnetic substance is

Options

A. 0
B. 1
C. `-1`
D. Less than 1

Answer

To determine the susceptibility of a perfectly diamagnetic substance, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Magnetic Susceptibility**:
- Magnetic susceptibility (χm) is a measure of how much a material will become magnetized in an applied magnetic field. It indicates the degree of magnetization of a material in response to an external magnetic field.

2. **Identify the Range of Susceptibility**:
- For diamagnetic materials, the susceptibility is always negative. The general range for magnetic susceptibility is from -1 to 0. This indicates that diamagnetic materials are repelled by magnetic fields.

3. **Perfectly Diamagnetic Substances**:
- A perfectly diamagnetic substance has a susceptibility of exactly -1. This means it will completely oppose an external magnetic field.

4. **Conclusion**:
- Therefore, the susceptibility of a perfectly diamagnetic substance is χm = -1.

### Final Answer:
The susceptibility of a perfectly diamagnetic substance is -1.

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