Substances which are repelled by the external magnetic field are called

Options

A. diamagnetic
B. paramagnetic
C. ferromagnetic
D. antiferromagnetic

Answer

To solve the question regarding substances that are repelled by an external magnetic field, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Magnetic Properties**:
- Substances can exhibit different magnetic behaviors when placed in an external magnetic field. The main types are diamagnetic, paramagnetic, ferromagnetic, and antiferromagnetic.

2. **Identifying Diamagnetic Substances**:
- Diamagnetic substances are characterized by the absence of unpaired electrons. This means that all the electrons in these substances are paired.

3. **Behavior in Magnetic Fields**:
- When an external magnetic field is applied, diamagnetic substances are not attracted to the magnetic field. Instead, they are repelled by it. This is a key characteristic of diamagnetism.

4. **Contrasting with Other Types**:
- In contrast, paramagnetic substances have unpaired electrons and are attracted to magnetic fields. Ferromagnetic substances can also be attracted to magnetic fields and can retain magnetization. Antiferromagnetic substances exhibit a complex behavior but are generally attracted to magnetic fields as well.

5. **Conclusion**:
- Based on the definitions and behaviors discussed, the substances that are repelled by an external magnetic field are classified as **diamagnetic**.

### Final Answer:
**Diamagnetic substances are repelled by an external magnetic field.**

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