Hard MCQ +4 / -1 PYQ · JEE Mains 2020

The one that can exhibit highest paramagnetic behaviour among the following is :

gly = glycinato; bpy = 2, 2'-bipyridine

  1. A [Fe(en)(bpy)(NH<sub>3</sub>)<sub>2</sub>]<sup>2+</sup>
  2. B [Pd(gly)<sub>2</sub>]
  3. C [Co(OX)<sub>2</sub>(OH)<sub>2</sub>]<sup>–</sup> ($\Delta$<sub>0</sub> &gt; P) Correct answer
  4. D [Ti(NH<sub>3</sub>)<sub>6</sub>]<sup>3+</sup>

Solution

[Co(OX)<sub>2</sub>(OH)<sub>2</sub>]<sup>–</sup> <br><br>(As here $\Delta$<sub>0</sub> &gt; P so those ligands act as strong field ligand and pairing happens.) <br><br><sub>27</sub>Co<sup>+5</sup> = [<sub>18</sub>Ar] 3d<sup>4</sup> 4s<sup>0</sup>( $t_{2g}^{2,1,1},e_g^{0,0}$ ) <br><br>It has highest number of unpaired e<sup>–</sup> s. so it is most paramagnetic.

About this question

Subject: Chemistry · Chapter: Coordination Compounds · Topic: Ligands and Coordination Number

This question is part of PrepWiser's free JEE Main question bank. 173 more solved questions on Coordination Compounds are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →