Chemistry Electrochemistry PMDC 2020
PMDC Verified Question 44 of 73
The common oxidation number of halogens is:
A
-1
B
+1
C
-2
D
0
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: -1
Concept:

Halogens are Group 17 elements (Fluorine, Chlorine, Bromine, Iodine) possessing seven valence electrons.

Solution:

  • To achieve a stable noble gas electron configuration (an octet), a halogen atom requires only one additional electron.


  • Due to their high electronegativity, they readily pull one electron from metals or less electronegative non-metals.


  • By gaining one electron, they predominantly form halide ions (e.g., \( F^-, Cl^-, Br^- \)) with an oxidation state of \( -1 \).


Why other options are incorrect:

While halogens (except Fluorine) can exhibit positive oxidation states (like \( +1, +3, +5, +7 \)) when bonded to more electronegative oxygen, the most common and dominant state across all halogens is \( -1 \).

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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