the choices are:
Answer 1
The greatest shielding occurs for electrons that have the greatest number of intermediate electrons between them and the nucleus. The valence shell of nitrogen is the 2nd energy level, so electrons in the 2p sublevel would experience the most shielding – there are 4 intermediate electrons between the nucleus and the 3 2p electrons in nitrogen .
answer 2
Effective nuclear charge Zeff = Z -S where Z is the nuclear charge on N(7) and S is the shielding of this nuclear charge by all other electrons. The Zeff is smaller for the most shielded electron:
Zeff [1] N 1s^2 2s62 2p^3
1s 6.67
2s 3.85 2p 3.83
3s no data 3p no data
The 3s and 3p are unoccupied. The 2s are less followed because ᴘᴇɴᴇтʀᴀтes the AO 1s more efficiently.
So the answer is 2p
[1] http://www.webelements.com/nitrogen/orbital_proper…