Explain why fluorine exhibit only -1 oxidation states whereas other halogens exhibit variable oxidation states ?

Fluorine exhibits only a -1 oxidation state because it is the most electronegative element on the periodic table. This means that fluorine has a very strong tendency to attract electrons towards itself in a chemical reaction. As a result, fluorine will always gain one electron to achieve a full outer shell of electrons, resulting in an oxidation state of -1.

On the other hand, other halogens such as chlorine, bromine, and iodine are less electronegative than fluorine and therefore exhibit variable oxidation states. These elements can gain or lose electrons in chemical reactions to achieve a full outer shell of electrons, resulting in a range of possible oxidation states. For example, chlorine can exhibit oxidation states of -1, 0, +1, +3, +5, and +7 depending on the specific compound and reaction conditions.