Chemistry Transition Elements SZABMU 2023
PMDC Verified Question 18 of 68
The binding energy of transition elements weakens progressively upto group:
A
III B
B
IV B
C
II B
D
V B
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: II B
Concept:

Binding energy in transition metals heavily relies on the "electron sea" generated by unpaired \(d\)-electrons. The more unpaired electrons, the stronger the metallic bonds.

Solution:

  • Binding energy is highest in the middle of the transition series (Group VI B) where the number of unpaired electrons is maximized.


  • Moving to the right of the series, electrons begin to pair up inside the \(d\)-orbitals, removing them from participation in strong metallic bonding.


  • This progressive pairing continues until Group II B (Zinc, Cadmium, Mercury), which has a fully paired \(d^{10}\) configuration.


  • Because they have zero unpaired \(d\)-electrons, Group II B metals have incredibly weak binding energies, leading to low melting points (e.g., Mercury is a liquid).


Why other options are incorrect:

  • Groups III B, IV B, and V B are on the left side of the table where binding energy is still increasing as unpaired electrons are added.

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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