To determine the bond order of O2 using molecular orbital theory, we need to consider the electron configuration of oxygen and then fill the molecular orbitals accordingly.Oxygen has 8 electrons, so O2 has a total of 16 electrons. The molecular orbitals for O2 can be filled in the following order: 1s, *1s, 2s, *2s, 2pz, 2px = 2py, *2px = *2py.Filling the molecular orbitals with 16 electrons, we get:1. 1s: 2 electrons2. *1s: 2 electrons3. 2s: 2 electrons4. *2s: 2 electrons5. 2pz: 2 electrons6. 2px = 2py: 4 electrons 2 electrons in each orbital 7. *2px = *2py: 2 electrons 1 electron in each orbital Now, we can calculate the bond order using the formula:Bond order = number of electrons in bonding orbitals - number of electrons in antibonding orbitals / 2Bond order = 2 + 2 + 4 - 2 / 2 = 6 / 2 = 3Therefore, the bond order of O2 is 3.