Which of the following compounds is responsible for the appearance of the brown ring?

[Fe(NO)(SO4)2]2−
[Fe(NO)2(H2O)4]3+
[Fe(NO)(SO4)2]
[Fe(NO)(H2O)5]2+

Correct answer: [Fe(NO)(H2O)5]2+

Solution

The brown ring is formed due to the presence of the nitrosonium ion, NO+, which is a strong electrophile and can react with water to form nitrous acid, resulting in the brown ring complex [Fe(NO)(H2O)5]2+.

Related JEE Advanced Chemistry questions

The pair(s) of coordination complexes/ions exhibiting the same kind of isomerism is(are) -
A 0.01 molal solution of a cobalt(III) chloride-ammonia complex, which dissociates completely, has a freezing point of -0.0558°C. Based on this data, how many chloride ions are present within the coordination sphere of the complex? [Kf for water = 1.86 K kg mol⁻¹]
What are the molecular shapes of the ammonia complexes formed by Ni²⁺, Pt²⁺, and Zn²⁺, respectively?
What are the spin-only magnetic moments (in Bohr Magneton) for the complexes [Cr(NH₃)₆]³⁺ and [CuF₆]³⁻, given that the atomic numbers of Cr and Cu are 24 and 29, respectively?
When K3[Fe(CN)6] reacts with freshly prepared FeSO4, a dark blue solid known as Turnbull's blue is formed. On the other hand, when K4[Fe(CN)6] reacts with FeSO4 in the complete absence of air, a white solid X is produced, which later turns blue when exposed to air. Additionally, if FeSO4 is mixed with NaNO3 and concentrated H2SO4 is carefully added along the side of a test tube, a brown ring forms. What is the chemical identity of precipitate X?
Match the complexes listed in Group-I with their respective characteristics in Group-II based on the given information. Group-I: (I) [Cr(CN)₆]³⁻ (II) [RuCl₆]²⁻ (III) [Cr(H₂O)₆]²⁺ (IV) [Fe(H₂O)₆]²⁺ Group-II: (P) The t₂g orbitals are occupied by 4 electrons. (Q) The spin-only magnetic moment is 4.9 BM. (R) Forms a low-spin complex. (S) The metal ion has an oxidation state of +4. (T) The complex is a d⁴ species. Given: Chromium (Cr) has an atomic number of 24, Ruthenium (Ru) has an atomic number of 44, and Iron (Fe) has an atomic number of 26. Choose the correct pairing of Group-I with Group-II.

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →