The ionization potential of N>O because
Ionization potential increases with decrease in size
N possess stable half filled p-orbital
The screening effect in N>O
O is more electropositive than N
As we learnt
Screening effect -
The actual charge experienced by the valence shell electron is called effective nuclear charge.
- wherein
The repulsive force experienced by valence shell electron from an inner shell electron is called a screening effect.
Due to electronic configuration, N has higher Ionisation potential than O.
Hence, the option number (2) is correct.