Chemistry Transition Elements SZABMU 2022
PMDC Verified Question 29 of 68
The transition element which doesn't show variable valency:
A
Sc
B
Cu
C
Zn
D
Cr
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Zn
Concept:

Transition metals generally exhibit variable valency because the energy gap between \(ns\) and \((n-1)d\) orbitals is small, allowing electrons from both to participate in bonding.

Solution:

  • Zinc (\(Zn\)) has the electron configuration \([Ar] \; 3d^{10} \; 4s^2\).


  • Because its \(d\)-subshell is completely full and extremely stable, it does not lose \(d\)-electrons under normal chemical conditions.


  • It only loses its two \(4s\) electrons, thereby strictly exhibiting a +2 oxidation state. Because it does not have multiple states, it does not show variable valency.


Why other options are incorrect:

  • Chromium (\(Cr\)) and Copper (\(Cu\)) show wide arrays of oxidation states (+1 to +6).

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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