PrepRung
Sign inSign up free

JEE Advanced 2016 Paper 1 · Chemistry · Coordination Compounds · medium

(s) about the following complex ions (atomic numbers: Fe=26, Co=27, Ni=28).

One or more options correct

Choose the correct statement(s) about the following complex ions (atomic numbers: Fe=26\mathrm{Fe}=26, Co=27\mathrm{Co}=27, Ni=28\mathrm{Ni}=28).
  1. A. [NiCl4]2−[\mathrm{NiCl_4}]^{2-} is tetrahedral and its spin-only magnetic moment is about 2.83 BM2.83\ \mathrm{BM}.
  2. B. [NiCl4]2−[\mathrm{NiCl_4}]^{2-} and [Ni(CN)4]2−[\mathrm{Ni(CN)_4}]^{2-} have the same geometry and the same number of unpaired electrons.
  3. C. [Co(NH3)6]3+[\mathrm{Co(NH_3)_6}]^{3+} is diamagnetic and involves d2sp3d^2sp^3 hybridisation.
  4. D. [Fe(H2O)6]3+[\mathrm{Fe(H_2O)_6}]^{3+} has a spin-only magnetic moment of about 5.92 BM5.92\ \mathrm{BM}.
Show answer and solution

Answer: A, C, D

(A) Correct. Cl−\mathrm{Cl^-} is a weak-field ligand and Ni2+\mathrm{Ni^{2+}} is d8d^8; the complex is sp3sp^3 tetrahedral with two unpaired electrons, μ=2×4=2.83 BM\mu=\sqrt{2\times4}=2.83\ \mathrm{BM}. (B) Incorrect. CN−\mathrm{CN^-} is a strong-field ligand which pairs the d8d^8 electrons, giving square planar dsp2dsp^2 [Ni(CN)4]2−[\mathrm{Ni(CN)_4}]^{2-} with zero unpaired electrons; the two ions differ in both geometry and magnetism. (C) Correct. Co3+\mathrm{Co^{3+}} is d6d^6; with the strong-field NH3\mathrm{NH_3} the six electrons pair in t2gt_{2g}, leaving two 3d3d orbitals free for d2sp3d^2sp^3 hybridisation, so the complex is diamagnetic. (D) Correct. Fe3+\mathrm{Fe^{3+}} is d5d^5 and water is a weak-field ligand, so all five electrons are unpaired, μ=5×7=5.92 BM\mu=\sqrt{5\times7}=5.92\ \mathrm{BM}.
Report a mistake

Original question written in the JEE Advanced 2016 Paper 1 pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake