A: In a diamagnetic substance each atom has a non-zero dipole moment but due to thermal agitation the individual dipoles ramein randomly oriented and, therefore, the net dipole moment in any finite volume of the substance remains zero.
R: On increasing the temperature the magnetism inside a perament magent increases.

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 both the assertion (A) and the reason (R) provided in the statement.

### Step 1: Understand the Assertion (A)
The assertion states that in a diamagnetic substance, each atom has a non-zero dipole moment, but due to thermal agitation, the individual dipoles remain randomly oriented, resulting in a net dipole moment of zero in any finite volume of the substance.

#### Explanation:
- **Diamagnetic substances** are characterized by having all their electrons paired. When electrons are paired, their magnetic moments cancel each other out, leading to a **net magnetic moment of zero** for each atom.
- The statement that each atom has a non-zero dipole moment is incorrect because, in diamagnetic materials, the paired electrons result in zero net dipole moment.

### Step 2: Understand the Reason (R)
The reason states that on increasing the temperature, the magnetism inside a permanent magnet increases.

#### Explanation:
- In permanent magnets, the magnetic domains are aligned, giving them a net magnetic moment.
- However, increasing the temperature increases thermal agitation, which can disrupt the alignment of these magnetic domains, leading to a decrease in magnetism. Therefore, this statement is also incorrect.

### Step 3: Conclusion
Since both the assertion (A) and the reason (R) are incorrect, the answer to the question is that both statements are false.

### Final Answer:
Both A and R are incorrect.

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