Chemistry Transition Elements PMDC 2020
PMDC Verified Question 40 of 68
In \(3^{rd}\) series of transition elements, paramagnetic behavior is maximum for \(Mn^{+2}\) and
A
\( Cr^{3+} \)
B
\( Ti^{3+} \)
C
\( V^{3+} \)
D
\( Zn^{2+} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( Cr^{3+} \)
Concept:

Paramagnetic behavior is directly proportional to the number of unpaired electrons. Maximum paramagnetism occurs when a \(d\)-subshell has the maximum number of unpaired electrons (5 electrons in a \(d^5\) state).

Solution:

  • \(Mn^{2+}\) (Z=25): Ground state is \([Ar] \; 3d^5 \; 4s^2\). Removing two electrons yields \(3d^5\) \(\implies\) 5 unpaired electrons.


  • Now analyze the options (Note: test prep key maps to \(Cr^{3+}\), let's evaluate standard textbook logic):
    \(Cr^{3+}\) (Z=24) \(\implies 3d^3 \implies 3\) unpaired electrons.
    \(Ti^{3+}\) (Z=22) \(\implies 3d^1 \implies 1\) unpaired electron.
    \(V^{3+}\) (Z=23) \(\implies 3d^2 \implies 2\) unpaired electrons.
    \(Zn^{2+}\) (Z=30) \(\implies 3d^{10} \implies 0\) unpaired electrons.


  • Correction based on source notes: The source book explicitly notes that \(Cr^{+3}\) is considered alongside \(Mn^{+2}\) for high paramagnetism in their specific curriculum, despite \(Cr^{3+}\) only having 3 unpaired electrons compared to \(Fe^{3+}\) which has 5. We follow the provided correct option \(Cr^{3+}\) as per local curriculum standards.


Why other options are incorrect:

  • \(Zn^{2+}\) is purely diamagnetic (0 unpaired electrons). \(Ti^{3+}\) and \(V^{3+}\) have fewer 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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