Chemistry S & P Block Elements SET 2019
PMDC Verified Question 69 of 104
Which element has the highest electron affinity among halogens?
A
F
B
I
C
Cl
D
Br
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Cl
Concept:

Electron affinity (EA) generally decreases (becomes less negative) down a group as atomic size increases. However, the halogens feature a major exception at the top of the group.

Solution:

  • While Fluorine (F) is the most electronegative element, its atomic size is exceptionally small.
  • Because of this tiny size, its 7 valence electrons are crowded in a very small 2p orbital, creating intense electron-electron repulsion.
  • When an incoming electron approaches F, it faces significant repulsive resistance, lowering the net energy released.
  • Chlorine (Cl) has a larger 3p orbital which comfortably accommodates the incoming electron with much less repulsion, releasing maximum energy.
  • Therefore, Chlorine (Cl) has the highest (most negative) electron affinity in the periodic table.


Why other options are incorrect:

  • F suffers from steric/electronic repulsion. Br and I have much larger sizes and thicker shielding, leading to weaker nuclear pull on the incoming electron.

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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