a. Electrons in bonding orbitals make the species more stable and electrons in antibonding orbitals make the species less stable.
b. Electrons in bonding orbitals make the species less stable and electrons in antibonding orbitals make the species more stable.
c. There is a net stabilization and the system is lower in energy when electrons are in the molecular orbitals than when they are in their individual atomic orbitals.
d. The stabilization from the electrons in bonding molecular orbitals is cancelled out by the destabilization caused by the electrons filling the antibonding molecular orbitals.
