The highest energy occupied molecular orbital in the f-f bond of the f2 molecule is

The basis of finding the answer to this problem is to know the electronic configuration of Fluorine. That would be: [He] 2s² 2p⁵. The valence electrons, which are the outermost electrons of the atom, are the ones that participate in bonding. Since the highest orbital for F is 2p, that means the highest energy occupied would be 2.