A: If a toroid uses bismuth for its core, then the field in the core will be slightly less than when the core is empty.
R: Bismuth is paramagnetic.

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 analyze the assertion and reason given in the question, we will break it down into steps.

### Step 1: Understand the Assertion
The assertion states that if a toroid uses bismuth for its core, then the magnetic field in the core will be slightly less than when the core is empty.

### Step 2: Understand the Reason
The reason provided is that bismuth is paramagnetic.

### Step 3: Identify the Nature of Bismuth
In reality, bismuth is not paramagnetic; it is actually a diamagnetic material. This means that bismuth will exhibit a weak repulsion from a magnetic field.

### Step 4: Analyze the Effect of a Diamagnetic Material
When a diamagnetic material like bismuth is placed in a magnetic field, it tends to move away from the stronger part of the field, leading to a reduction in the overall magnetic field strength within the material compared to the surrounding area.

### Step 5: Conclusion on the Assertion and Reason
Since the assertion is true (the magnetic field in the core will be slightly less when using bismuth), but the reason is false (bismuth is not paramagnetic), we conclude that:
- The assertion is true.
- The reason is false.

### Final Answer
Thus, the correct answer is that the assertion is true, but the reason is false.

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