Chemistry Transition Elements UHS 2023
PMDC Verified Question 16 of 68
Which of the following is correct electronic configuration of iron (II) ion (atomic number of Fe is = 26)?
A
\( [Ar] \; 4s^{0}, 3d^{6} \)
B
\( [Ar] \; 4s^{2}, 3d^{6} \)
C
\( [Ar] \; 4s^{2}, 3d^{4} \)
D
\( [Ar] \; 4s^{2}, 3d^{5} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( [Ar] \; 4s^{0}, 3d^{6} \)
Concept:

When a transition metal forms a cation, electrons are always removed from the outermost shell (highest \(n\) value) first.

Solution:

  • The ground state configuration of neutral Iron (\(Z = 26\)) is \([Ar] \; 4s^2 \; 3d^6\).


  • The Iron(II) ion, or \(Fe^{2+}\), indicates that the atom has lost 2 electrons.


  • These electrons are removed from the highest energy level, which is the \(4s\) orbital.


  • Removing the two \(4s\) electrons leaves the configuration as: \([Ar] \; 4s^0 \; 3d^6\).


Why other options are incorrect:

  • Option B: This is the configuration for neutral Iron, not the ion.


  • Option C/D: Incorrectly removes electrons from the \(d\)-subshell while leaving the \(s\)-subshell full.

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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