Concept: Molecular Orbital Theory (MOT)

Molecular Orbital Theory describes the bonding in molecules by considering the combination of atomic orbitals to form molecular orbitals. These molecular orbitals can be bonding (lower energy, stabilize the molecule) or antibonding (higher energy, destabilize the molecule). The filling of these orbitals follows Hund's rule and Pauli's exclusion principle. The order of filling for diatomic molecules depends on the atoms involved (e.g., for O\u2082 and F\u2082, \u03c32p is lower than \u03c02p, while for N\u2082 and lighter molecules, \u03c02p is lower than \u03c32p).

Why (B) is correct:

Let's analyze the molecular orbital configuration for O\u2082 and O\u2082\u207b:

• O\u2082 (16 electrons): \u03c31s\u00b2 \u03c3*1s\u00b2 \u03c32s\u00b2 \u03c3*2s\u00b2 \u03c32p\u00b2 \u03c02p\u2074 \u03c0*2p\u00b2. The last two electrons enter the antibonding \u03c0*2p orbitals.

• O\u2082\u207b (17 electrons): When O\u2082 forms O\u2082\u207b, one electron is added. This electron will enter the next available molecular orbital, which is an antibonding \u03c0*2p orbital. So, the configuration becomes \u03c31s\u00b2 \u03c3*1s\u00b2 \u03c32s\u00b2 \u03c3*2s\u00b2 \u03c32p\u00b2 \u03c02p\u2074 \u03c0*2p\u00b3. Therefore, during O\u2082\u207b formation, one electron is added to the antibonding molecular orbitals.

Option Analysis:

• A) During O\u2082\u207a formation, one electron is removed from the bonding molecular orbitals.
  O\u2082 has its highest occupied molecular orbitals (HOMO) as antibonding \u03c0*2p. When O\u2082 forms O\u2082\u207a, an electron is removed from the \u03c0*2p antibonding orbital, not a bonding orbital. So, this statement is incorrect.

• B) During O\u2082\u207b formation, one electron is added to the antibonding molecular orbitals.
  As explained above, the additional electron in O\u2082\u207b enters the \u03c0*2p antibonding orbital. This statement is correct.

• C) During N\u2082\u207a formation, one electron is removed from the antibonding molecular orbitals.
  For N\u2082 (14 electrons): \u03c31s\u00b2 \u03c3*1s\u00b2 \u03c32s\u00b2 \u03c3*2s\u00b2 \u03c02p\u2074 \u03c32p\u00b2. The HOMO is the bonding \u03c32p orbital. When N\u2082 forms N\u2082\u207a, an electron is removed from the \u03c32p bonding orbital, not an antibonding orbital. So, this statement is incorrect.

• D) During He\u2082\u207a formation, one electron is removed from the bonding molecular orbitals.
  For He\u2082\u207a (3 electrons): \u03c31s\u00b2 \u03c3*1s\u00b9. The electron is removed from the \u03c3*1s antibonding orbital (if we consider forming He\u2082\u207a from He\u2082, which is unstable, or from He, then adding an electron to form He\u2082\u207a). If we consider forming He\u2082\u207a from two He atoms and then removing an electron, the bonding orbital \u03c31s would be filled first. However, the statement implies removal from an existing He\u2082 molecule, which doesn't exist stably. More accurately, if we consider the formation of He\u2082\u207a from He and He\u207a, the configuration is \u03c31s\u00b2 \u03c3*1s\u00b9. If an electron were removed from this, it would be from \u03c3*1s. If we consider forming He\u2082\u207a from He\u2082 (hypothetical), the electron would be removed from \u03c3*1s. So, this statement is incorrect.

Correct Answer: (B)