Which of the following statements are correct ?

Options

A. Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic
B. Ferrimagnetic substances do not lose ferrimagnetism on heating and remain ferrimagnetic
C. Antiferromagnetic substances have domain structures similar to ferromagnetic substances and their magnetic moments are not cancelled by each other
D. In ferromagnetic substances , all the domains get oriented in the direction of magnetic field and remain as such even after removing magnetic field

Answer

To determine which statements about ferrimagnetic and anti-ferrimagnetic substances are correct, we will analyze each statement one by one based on the principles of magnetism.

### Step-by-Step Solution:

1. **Evaluate Statement 1**: "Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic."
- **Analysis**: This statement is correct. Ferrimagnetic materials exhibit magnetism due to the alignment of magnetic moments in opposite directions, but when heated, the thermal energy disrupts this alignment, causing them to lose their magnetism and behave like paramagnetic materials.

2. **Evaluate Statement 2**: "Ferrimagnetic substances do not lose ferrimagnetism on heating and remain ferrimagnetic."
- **Analysis**: This statement is incorrect. As established in the analysis of Statement 1, ferrimagnetic substances do lose their magnetism upon heating and do not remain ferrimagnetic.

3. **Evaluate Statement 3**: "Anti-ferrimagnetic substances have domain structures similar to ferrimagnetic, and their magnetic moments are not cancelled by each other."
- **Analysis**: This statement is false. Anti-ferrimagnetic materials have magnetic moments that are aligned in opposite directions, which results in cancellation of their magnetic moments. This is different from ferrimagnetic materials, where the moments do not completely cancel out.

4. **Evaluate Statement 4**: "Ferrimagnetic substances have all domains oriented in the direction of the magnetic field and remain as such even after removing the magnetic field."
- **Analysis**: This statement is correct. Ferrimagnetic materials can retain some magnetization after the external magnetic field is removed due to their domain structure, which allows them to exhibit permanent magnetism.

### Conclusion:
- **Correct Statements**:
- Statement 1: True
- Statement 2: False
- Statement 3: False
- Statement 4: True

Thus, the correct statements are 1 and 4.