Question

The true statement(s) regarding the brown ring test carried out in the laboratory for the detection of NO\(_3^-\) is/are

• A. Brown ring is due to the formation of the iron nitrosyl complex.
• B. Concentrated nitric acid is used for the test.
• C. The complex formed in the reaction is [Fe(CN)₆]NO₂²⁻.
• D. The brown colored complex is paramagnetic in nature.

Hint:

The brown ring test is used to detect NO₃⁻ by forming a brown nitrosyl complex, which is paramagnetic in nature.

Answer 1

The Correct Option is A, D

Step 1: Understanding the brown ring test.
In the brown ring test, nitrate ions (NO\(_3^-\)) react with iron(II) sulfate to form a brown-colored iron nitrosyl complex, which is paramagnetic. The test is used to confirm the presence of nitrate ions.
Step 2: Conclusion.
The correct statements are that the brown ring is due to the formation of the iron nitrosyl complex, and the brown complex is paramagnetic. Thus, the correct options are (A) and (D).