Question

ionisation enthalpy of nitrogen is more than oxygen why..?

Answer 1

Oxygen has low ionisation energy (than that of nitrogen ). It is due to an electron being added to an already half full orbital in
oxygen , which results in electron electron repulsion, which will lower the ionisation energy . ... Nitrogen also has the added stability of a half filled shell of electrons in the 2p shell.

Answer 2

kyuki nitrogen k outer orbital m 5 electron's hote h jabki oxygen m 6 electron's hote h so prabhavi nabhikiy avesh k karan nitrogen k electrons nikalne easy hote h so that why ionization enthalpy is more than oxygen

hope it's helps you