Which one of the following elements, based on their electronic configurations, has the highest ionization enthalpy?
1.
2.
3.
4.
Hint: Element having half-filled and fully-filled electronic configuration has high ionization enthalpy.
The electronic configuration of options (b) and (d) have exactly half-filled 3p orbitals (b) represents phosphorus and (c) represents arsenic but (b) is smaller in size than (d).
Hence, (b) has the highest ionization enthalpy increases left to right in the periodic table as the size decreases.
