During which of the following ionizations does the magnetic behaviour change from paramagnetic to diamagnetic, accompanied by an increase in bond order?

Step-by-step solution

Let us evaluate the magnetic properties and bond order (BO) for each process using Molecular Orbital Theory: (1) N ₂ N ₂⁺ + e ⁻ N ₂ (14 electrons): Diamagnetic, BO = 10 - 4 2 = 3.0 N ₂⁺ (13 electrons): Paramagnetic, BO = 9 - 4 2 = 2.5 Change: Diamagnetic to Paramagnetic, BO decreases. (2) O ₂ O ₂⁺ + e ⁻ O ₂ (16 electrons): Paramagnetic, BO = 10 - 6 2 = 2.0 O ₂⁺ (15 electrons): Paramagnetic, BO = 10 - 5 2 = 2.5 Change: Paramagnetic to Paramagnetic, BO increases. (3) C ₂ C ₂⁺ + e ⁻ C ₂ (12 electrons): Diamagnetic, BO