A: A magnetize needle in a uniform magnetic field experiences a torque but no net force, however, an iron hail near a bar magnet experiences a force of attraction as well as torque.
R: Bar magnet creates non-uniform magnetic field.

Options

A. If both Assertion & Reason are the true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reson is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we need to analyze the assertion (A) and the reason (R) provided regarding the behavior of a magnetized needle in a uniform magnetic field and an iron nail near a bar magnet.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that a magnetized needle in a uniform magnetic field experiences a torque but no net force.
- This is true because in a uniform magnetic field, the forces acting on the two poles of the magnetized needle (north and south) are equal in magnitude and opposite in direction, resulting in a torque that tends to align the needle with the magnetic field but no net translational force.

2. **Understanding the Reason (R)**:
- The reason states that a bar magnet creates a non-uniform magnetic field.
- This is also true. A bar magnet generates a magnetic field that varies in strength and direction depending on the distance from the magnet. Near the magnet, the field is stronger and changes rapidly, leading to a non-uniform field.

3. **Analyzing the Behavior of the Iron Nail**:
- An iron nail placed near a bar magnet experiences both a force of attraction and a torque.
- The force of attraction occurs because the non-uniform magnetic field exerts different forces on the different parts of the nail, leading to a net force pulling it towards the magnet.
- Additionally, the nail can also experience torque due to the non-uniform field, which can cause it to rotate and align itself with the magnetic field lines.

4. **Conclusion**:
- Both the assertion and the reason are correct. The assertion correctly describes the behavior of a magnetized needle in a uniform magnetic field, and the reason explains why an iron nail experiences both force and torque when placed in the non-uniform magnetic field of a bar magnet.

### Final Answer:
Both the assertion (A) and the reason (R) are correct, and the reason correctly explains the assertion.

---