JEE Main · 2022 · 26 Jul 2022 · Shift 2 · Coordination Compounds

The metal complex that is diamagnetic is (Atomic number : Fe, 26; Cu, 29)

(A) $K_{3} [Cu (CN)_{4}]$ ✓ Correct
(B) $K_{2} [Cu (CN)_{4}]$
(C) $K_{3} [Fe (CN)_{4}]$
(D) $K_{4} [FeCl_{6}]$

Answer: (A)

Solution

K_{3} [Cu (CN)_{4}]

, the oxidation state of copper is +1.

Cu^{+}

has the electronic configuration

[Ar] 3 d^{10}

, with all d-orbitals fully filled and no unpaired electrons, making it diamagnetic. The other complexes have unpaired electrons and are paramagnetic. Answer: (A).

JEE Main · 2022 · 26 Jul 2022 · Shift 2 · Single correct option

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