Which of the following species absorb maximum energy in its HOMO-LUMO electronic transition? — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: The energy absorbed in a HOMO-LUMO transition is directly proportional to the gap between these orbitals. A higher bond order and greater stability generally translate to a larger orbital gap. Step 2: Nitrogen (N2) has a highly stable triple bond (bond order = 3.0) with completely filled bonding molecular orbitals and a very low-lying unoccupied antibonding orbital, resulting in an exceptionally large HOMO-LUMO gap. Step 3: Due to this massive energy gap, N2 requires the absorption of maximum energy for this transition compared to O2, C2, or N2-. This corresponds to option (d).