Question

Second ionization enthalpy of nitrogen is less than first ionization enthalpy. Why?​

Answer 1

Answer:

The second ionization energy of oxygen is higher than for nitrogen. ... It is because oxygen atom is smaller due to a higher effective nuclear charge Zeff=Z−S , where S is approximated to be the number of core electrons and Z is the atomic number.

Answer 2

Explanation:

Because nitrogen has half filled electron in its ground state .. that's why it's first ionisation enthalpy is very high as compared to its second one