Why is fluorine the best oxidising agent, but also the most basic?
Fluorine is the most electronegative element.
But due to its high effective nuclear charge it holds up its electron density very tightly, moreover its a non-metal so preferably accepts electron to form stable (F–) ion which has configuration of Ne.
F2 ------> F- + e- is very favorable therefore it gets reduced very easily (reduced form F- is very stable than F2) and so it oxidises other elements and self gets reduced.