Question

Which of the following statements is correct regarding molecular orbital theory (MOT)?

• A. Energy of bonding orbital is less than that of anti-bonding orbital
• B. Energy of bonding orbital is more than that of anti-bonding orbital
• C. Bonding orbitals are monocentric
• D. Bonding orbitals follow (n+ l) rule
  

Answer 1

The correct option is A Energy of bonding orbital is less than that of anti-bonding orbital

There is an increase in the electron density between the nuclei in bonding orbitals, and a decrease in the electron density in antibonding orbitals.
Placing an electron in the bonding orbital stabilizes the molecule because it is in between the two nuclei. Conversely, placing electrons into the antibonding orbital will decrease the stability of the molecule. More the stabilily, lesser will be the energy of an orbital, hence the energy of a bonding orbital is less than that of an anti-bonding orbital and electron filling is done from the bonding orbitals (lower energy).