Chemistry Electrochemistry SZABMU 2022
PMDC Verified Question 28 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 keep track of electron distribution in compounds. If an element has not formed bonds with any other unique element, there has been no electron transfer.

Solution:

  • By fundamental IUPAC definition, any element existing in its uncombined, pure, free state (whether monoatomic like \( He \), diatomic like \( O_2 \), or polyatomic like \( S_8 \)) has not gained or lost any electrons relative to its neutral atomic state.


  • Therefore, its assigned oxidation number is exactly Zero.


Why other options are incorrect:

Positive and negative oxidation states only arise when an atom forms bonds with an atom of a different element with differing electronegativity.

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