Assertion (A): If one arm of a `U-`tube containing a diamagnetic solution is placed in between the poles of a strong magnet with the level in line with the field, the level of the solution falls,
Reason (R ): Diamagnetic substances do not aligned with the field

Options

A. If both Assertain and Reason are true and Reason is the correct explanation of Assertain
B. If both Assertain and Reason are true but Reason is not correct explantion of Assertain
C. If Assertion is true but Reason is false
D. If Assertion is false but Reason in true.

Answer

To solve the given problem, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that if one arm of a U-tube containing a diamagnetic solution is placed between the poles of a strong magnet, the level of the solution falls.
- This implies that the diamagnetic solution experiences a change in height when subjected to a magnetic field.

2. **Understanding the Reason (R)**:
- The reason states that diamagnetic substances do not align with the magnetic field.
- Diamagnetic materials are characterized by their tendency to create an induced magnetic field in the opposite direction when exposed to an external magnetic field. This results in a repulsive effect.

3. **Analyzing the Effect of the Magnetic Field**:
- When the U-tube is placed in a magnetic field, the diamagnetic solution will experience a force due to the magnetic field.
- Since diamagnetic substances do not align with the magnetic field, they will not be attracted to the field. Instead, they will experience a slight repulsion.

4. **Behavior of the Liquid in the U-Tube**:
- The magnetic field creates a pressure difference in the U-tube. The arm of the U-tube that is closer to the stronger part of the magnetic field will experience a decrease in liquid level.
- As a result, the level of the solution in that arm falls, while the level in the other arm rises.

5. **Conclusion**:
- Since the assertion states that the level of the solution falls, and we have established that this is true due to the behavior of diamagnetic substances in a magnetic field, we conclude that both the assertion and the reason are correct.
- Furthermore, the reason provides a correct explanation for the assertion.

### Final Answer:
Both the assertion (A) and the reason (R) are correct, and the reason is the correct explanation for the assertion.

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