Question

An element, which never as a positive oxidation state in any of its compounds, is:

• A. boron
• B. oxygen
• C. chlorine
• D. fluorine

Answer 1

The correct option is D fluorine

Element	Oxidation State	Exceptions
Boron	always +3
Oxygen	usually -2	except in peroxides and $F_{2}O$
Chlorine	usually -1	except in compounds with $O$ or $F$
Fluorine	always -1

Since, fluorine is the most elecronegative element in the periodic table, it exihibits and oxidation state of -1 always with no exceptions. Hence answer is $D$.