Final answer:
The 4f subshell has the highest energy among the choices provided, which are 4s, 4p, 4d, and 4f. Energy levels generally increase from s to p to d to f within the same principal energy level, with the 4f being the highest in this scenario.
Step-by-step explanation:
When comparing subshells 4s, 4p, 4d, and 4f, assuming they all share the same principal quantum number (n=4), the general trend in the energy of subshells is s < p < d ≈ f. Therefore, within the same principal energy level, the 4f subshell would have the highest energy, followed by the 4d, 4p, and then the 4s subshell having the lowest energy among them. This energy hierarchy is due to the influence of the angular momentum quantum number that accompanies each type of subshell (s, p, d, f), where a higher angular momentum generally means a higher energy level within the same principal quantum number.
However, it is also crucial to note that electrons fill the 4s subshell before the 3d because the 4s is slightly lower in energy than the 3d subshell. This is reflected in the electron configuration pattern and the structure of the periodic table. Despite their positions in energy levels, when filling orbitals, 4s gets filled before 3d due to these slight differences in energy caused by electron interactions and quantum mechanical principles.