Nuclear charge actually experienced by an electron is termed as effective nuclear charge The effective nuclear `Z^(**)` actually depends on type of shell and orbital in which electron is actually present. The relative extent to which the various orbitals penetrate is .`s gt p gt d gt f` (for the same value of n)
The phenomenon in which penulitmate shell electrons act as screen or shield in between nucleus adn valence shell electrons and there by reducing nuclear charge is known as sheilding effect. The penultimate shell electrons repel the valence shell electron to keep them loosely held with nucleus . It is thus evident that more is the shielding effect, lesser is the effective nuclear charge and lesser is the ionizatio energy.
Ionization energy is not influenced by :

Options

A. size of atom
B. Effective nuclear charge
C. Electron present in inner shell
D. Change in entropy

Answer

D