Account for the following :
Two S - O bond lengths in `SO_(2)` are equal.
(ii) Fluorine shows only - 1 oxidation state in its compounds.

Explanation

(i) Sulphur forms one `p pi -p pi` and one `p pi -d pi` bond with oxygen. However, the two S - O bonds are equal (143 pm) because of resonance between two of them.

(ii) Fluorine is the most electronegative element known, it cannot share its unpaired electron with an element more electronegative than itself and hence cannot show an oxidation state of +1.
Moreover, it does not have empty d-orbital and hence it cannot expand its oxidation state to higher positive oxidation state of +3, +5, +7 etc.