Assertion(A) : Aniline hydrogen sulphate on heating froms a mixture of o- and p-amineo- sulphonic acid .
Reason (R ) : The suphonic acid is electron withdrawing group.

Options

A. If both (A) and (R ) ar true, and (R ) is the correct explanation of (A).
B. If both (A) and (R ) are true , and (R ) is not the correct explanation of (A).
C. If (A) is true , but (R ) is false .
D. If both (A) and (R ) are false .

Explanation

To solve the question, we need to analyze the assertion and reason provided:

### Step 1: Understand the Assertion
The assertion states that "Aniline hydrogen sulfate on heating forms a mixture of o- and p-amino sulfonic acid."
- Aniline hydrogen sulfate (C6H5NH3^+ HSO4^-) can be heated to produce aniline (C6H5NH2) and sulfuric acid (H2SO4).
- When aniline undergoes sulfonation (reaction with sulfuric acid), it can lead to the formation of both ortho (o-) and para (p-) amino sulfonic acid due to the presence of the amino group (NH2) which is an ortho/para directing group.

### Step 2: Analyze the Reason
The reason states that "The sulfonic acid is an electron withdrawing group."
- The sulfonic acid group (SO3H) is indeed an electron-withdrawing group. This means that it decreases the electron density of the aromatic ring.
- However, in the context of the assertion, the amino group (NH2) is the one that is influencing the positions where sulfonation occurs. The NH2 group is an electron-donating group, which increases the electron density at the ortho and para positions, making them more reactive towards electrophilic substitution.

### Step 3: Conclusion
- The assertion is correct because heating aniline hydrogen sulfate does lead to the formation of a mixture of ortho and para amino sulfonic acids.
- The reason is also true, as the sulfonic acid group is indeed an electron-withdrawing group. However, it does not correctly explain the assertion because the amino group (NH2) is responsible for directing the sulfonation to the ortho and para positions.

### Final Answer
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the answer is:
**Option B: Both assertion and reason are true, but reason is not the correct explanation of assertion.**

---