Which is more stable, half filled or full filled? Why?

subshells have two reasons of stability-

1) half filled and full filled subshells lead to symmetry as symmetry always increases stability in the nature.

2) in half filled and full filled subshells there are maximum no Of exchanges so exchanges releases energy so it increase stability ... Exchange of e-s also can b understood as delocalization of e-s which is similar like resonance and resonance always increases stability