JEE MainChemistryPractical Chemistry
Match List I with List II regarding the observations when aqueous solutions of the given metal cations are treated with potassium ferrocyanide, K ₄[ Fe ( CN )₆] . List I (Metal Cation) List II (Observation) (A) Cu ²⁺ (I) White precipitate (B) Fe ³⁺ (II) Chocolate brown precipitate (C) Zn ²⁺ (III) Prussian blue precipitate (D) Fe ²⁺ (IV) White precipitate which rapidly turns blue on exposure to air Choose the correct
Options
- A(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
- B(A)-(II), (B)-(IV), (C)-(I), (D)-(III)
- C(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
- D(A)-(II), (B)-(III), (C)-(IV), (D)-(I)
Correct answer
A. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
Step-by-step solution
When aqueous solutions of metal cations react with potassium ferrocyanide, K ₄[ Fe ( CN )₆] : (A) Cu ²⁺ reacts to form a chocolate brown precipitate of cupric ferrocyanide, Cu ₂[ Fe ( CN )₆] . (B) Fe ³⁺ reacts to form a Prussian blue precipitate of ferric ferrocyanide, Fe ₄[ Fe ( CN )₆]₃ . (C) Zn ²⁺ reacts to form a white or bluish-white precipitate of K ₂ Zn ₃[ Fe ( CN )₆]₂ . (D) Fe ²⁺ reacts to form a white precipitate of Everitt's salt, K ₂ Fe [ Fe ( CN )₆] , which rapidly oxidizes in air to form Prussian blue.