Final answer:
Bromine (Br) has the same 4s and 4p configuration in the fourth principal energy level as chlorine (Cl) has for its 3rd principal energy level, which is [Ar]4s² 4p⁵.
Step-by-step explanation:
The question revolves around identifying the element which has the same 4s and 4p configuration in the fourth principal energy level as chlorine (Cl) has for its 3rd principal energy level. Chlorine has an electron configuration of [Ne]3s² 3p⁵ which means it has two electrons in the 3s subshell and five electrons in the 3p subshell, resulting in a 3s² 3p⁵ configuration.
Considering the elements in the fourth period of the periodic table and their analogous relationship with elements in the third period, we look for an element with a 4s² 4p⁵ configuration. This matches the electron configuration of bromine (Br), which is [Ar]4s² 4p⁵.