Chemistry Transition Elements ETEA 2022
PMDC Verified Question 31 of 68
Which of the following ions forms most stable complex compound?
A
\( Cu^{+2} \)
B
\( Ni^{+2} \)
C
\( Fe^{+2} \)
D
\( Mn^{+2} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( Cu^{+2} \)
Concept:

The stability of coordination complexes formed by divalent first-row transition metal ions generally follows the Irving-Williams Series.

Solution:

  • The Irving-Williams series states that complex stability increases as the ionic radius decreases and the effective nuclear charge (charge density) increases across the period.


  • The stability order for \(+2\) ions is:
    \(Mn^{2+} < Fe^{2+} < Co^{2+} < Ni^{2+} < Cu^{2+} > Zn^{2+}\)


  • \(Cu^{2+}\) possesses the highest charge density and experiences additional stabilization due to Jahn-Teller distortion, allowing it to form the most thermodynamically stable complexes among the choices provided.


Why other options are incorrect:

  • They lie earlier in the Irving-Williams series, possessing larger ionic radii and lower charge densities than \(Cu^{2+}\).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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