Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However, oxygen has lower ionisation enthalpy than nitrogen. Explain.

Explanation

Nitrogen has stable half filled configuration `2s^(2)2p^(3)`. So removal of one electron will require more energy than oxygen. Similarly, in nitrogen, addition of one electron will require energy (andothermic) while in oxygen, addition of one electron will release energy (exothermic).