Chemistry Electrochemistry SZABMU 2024
PMDC Verified Question 6 of 73
Oxidation number of an element in free state is:
A
Negative
B
Positive
C
Zero
D
1
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Zero
Concept:

Oxidation numbers track the shift of electron density caused by bonding between atoms of different electronegativities.

Solution:

  • When an element is in its free, uncombined elemental state (e.g., \( Fe_{(s)}, O_{2(g)}, S_{8(s)} \)), all atoms in the structure are identical.


  • Because they have identical electronegativity, no atom can pull electrons away from another.


  • With zero net charge transfer, the IUPAC assigned oxidation number is exactly Zero.


Why other options are incorrect:

Positive and negative oxidation states only exist when an element forms compounds with other elements.

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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