Final answer:
Sodium (Na) has a higher first ionization energy than Rubidium (Rb) because it is located in a higher period and to the right of Rb in the periodic table.
Step-by-step explanation:
The question asks which element between Na (Sodium) and Rb (Rubidium) has the higher first ionization energy. Ionization energy is the energy required to remove an electron from a gaseous atom or ion. According to trends in the periodic table, ionization energy increases as you move from left to right across a period and decreases as you move down a group.
In this case, Na is located to the right of Rb in the periodic table and also resides in a higher period than Rb. Therefore, Sodium (Na) will have a higher first ionization energy compared to Rubidium (Rb). It can be inferred from the trend that the element at the bottom left (which is Rb in this case) will have the lowest first ionization energy in its group.