Ionization Potential of Elements
Ionization potential is the energy required to remove an electron from an atom or ion in its gaseous state. The lower the ionization potential, the easier it is to remove an electron from the atom.

Ionization Potential of Elements in the Question
1) Li (Lithium): Lithium has an ionization potential of 5.39 eV.
2) He (Helium): Helium has an ionization potential of 24.59 eV.
3) N (Nitrogen): Nitrogen has an ionization potential of 14.53 eV.
4) N (Nitrogen): Nitrogen has an ionization potential of 14.53 eV.

Least Ionization Potential
Among the given elements, Helium (He) has the least ionization potential of 24.59 eV. This means that it requires the least amount of energy to remove an electron from a helium atom compared to the other elements listed. This is because helium has a full valence shell with 2 electrons, making it stable and less likely to lose an electron.
In contrast, Lithium, Nitrogen, and Nitrogen all have higher ionization potentials, indicating that it is more difficult to remove an electron from these atoms. Nitrogen and Nitrogen have the same ionization potential, which is higher than that of Lithium.
Therefore, among the options provided, Helium has the least ionization potential.