In the ground state, an atom of each of the elements in Group 2 has a different first ionization energy (option 2)
Explanation:
Ionization energy is the energy needed to start an electron to a gaseous atom, isolated and in a fundamental state. The electrons of the last layer are always lost, which are the weakest attracted to the nucleus.
In a group the atoms have the same electronic structure in the outermost layer. But when lowering in the same group the electrons are in layers increasingly distant from the nucleus, being less and less attracted. The size of the atom increases as the number of electronic layers increases, increasing the atomic radius when descending in a group. But electrons are farther from the nucleus, and easier their expulsion will be. That is, its extraction from the atom is facilitated. Then the ionization energy decreases as it descends in a group. In other words, ionization energy is a function of the atomic radius; The larger the radius, the smaller the amount of energy required to remove the electron from the outermost orbital.
Finally, in the ground state, an atom of each of the elements in Group 2 has a different first ionization energy (option 2)
