Question

Which one of the following elements show different oxidation states?

• A. Sodium
• B. Fluorine
• C. Chlorine
• D. Potassium

Answer 1

The correct option is C Chlorine

Sodium is alkali metal with $n{s}^1$ configuration, thus shows oxidation of +1 only.
Fluorine has electronic configuration of $2s^{2}2p^5$ and therefore can show oxidation state of -1 only.
Chlorine has electronic configuration of $3s^{2}3p^5$ and has vacant d -orbital, therefore can show oxidation state of -1, along with other states as 0, +1, +3, +4, +5, or +7, in compounds containing $O$ or $F$
potassium is an alkali metal with $n{s}^1$ valence shell, thus shows +1 oxidation only.
Therefore option C is correct.