Chemistry Transition Elements ETEA 2023
PMDC Verified Question 19 of 68
Which one has one unpaired electron in the valence shell?
A
\( Zn^{+2} \)
B
\( Cu^{+} \)
C
\( Ti^{+3} \)
D
\( Fe^{+2} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: \( Ti^{+3} \)
Concept:

Write the electron configuration of each ion to count the number of unpaired electrons remaining in the \(d\)-subshell.

Solution:

  • \(Zn^{2+}\): Neutral Zn is \(3d^{10} \; 4s^2\). \(Zn^{2+}\) is \(3d^{10}\). All electrons are paired (0 unpaired).


  • \(Cu^{+}\): Neutral Cu is \(3d^{10} \; 4s^1\). \(Cu^{+}\) is \(3d^{10}\). All electrons are paired (0 unpaired).


  • \(Fe^{2+}\): Neutral Fe is \(3d^6 \; 4s^2\). \(Fe^{2+}\) is \(3d^6\). It has 4 unpaired electrons.


  • \(Ti^{3+}\): Neutral Ti is \(3d^2 \; 4s^2\). Removing three electrons leaves \(3d^1\). It has exactly 1 unpaired electron.


Why other options are incorrect:

  • As calculated, the other ions possess either 0 or 4 unpaired electrons.

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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