A: Reaction of carboxylic acid with hydrazoic acid in the presence of conc. `H_(2)SO_(4)` to form primary amine is called Schmidt reaction.
R: In this reaction isocyanate intermediate is formed.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason 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-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the reaction of carboxylic acid with hydrazoic acid in the presence of concentrated sulfuric acid (H₂SO₄) to form a primary amine is called the Schmidt reaction.
- This is true. The Schmidt reaction involves the conversion of carboxylic acids into primary amines through the reaction with hydrazoic acid.

2. **Understanding the Reason (R)**:
- The reason states that in this reaction, an isocyanate intermediate is formed.
- This is also true. During the Schmidt reaction, an isocyanate intermediate is indeed formed before the final product (the primary amine) is obtained.

3. **Examining the Relationship Between A and R**:
- While both the assertion and the reason are true, we need to determine if the reason is the correct explanation for the assertion.
- The formation of the isocyanate intermediate is a part of the mechanism of the Schmidt reaction, but it does not directly explain why the reaction itself is called the Schmidt reaction. The naming of the reaction is based on the overall transformation of carboxylic acids to primary amines, not solely on the formation of the isocyanate.

4. **Conclusion**:
- Therefore, the assertion is true, and the reason is true, but the reason is not the correct explanation for the assertion.
- The correct answer is that both A and R are true, but R is not the correct explanation for A.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is true, but it is not the correct explanation for the assertion.
- Thus, the answer is: **Assertion and Reason are true, but Reason is not the explanation for Assertion.**

---