Chemistry Transition Elements ETEA 2024
PMDC Verified Question 6 of 68
\( Cu^{2+} \) salt solution is blue in colour due to transition of electrons from
A
d to d orbital
B
p to p orbital
C
p to d orbital
D
s to p orbital
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: d to d orbital
Concept:

The color of transition metal complexes is explained by Crystal Field Theory, which describes the splitting of degenerate \(d\)-orbitals into different energy levels.

Solution:

  • The \(Cu^{2+}\) ion has a \(3d^9\) electron configuration, meaning its \(d\)-subshell is partially filled.


  • When surrounded by water ligands in a solution, the 5 previously equal-energy \(d\)-orbitals split into a lower energy set and a higher energy set.


  • Electrons in the lower set absorb specific wavelengths of visible light (red/orange) and jump to the vacant spots in the higher energy set.


  • This jump occurs exclusively between \(d\)-orbitals and is known as a \(d-d\) transition. The transmitted (unabsorbed) light hits our eyes as blue.


Why other options are incorrect:

  • Transitions between entirely different subshells (like \(s ightarrow p\) or \(p ightarrow d\)) typically require much higher energy, corresponding to the ultraviolet spectrum, not the visible spectrum.

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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