What is the maximum number of electrons that can occupy a single d subshell?

The maximum number of electrons that can occupy a single d subshell is 10. In electron configuration, a d subshell is made up of five orbitals, and each of these orbitals can hold a maximum of two electrons, according to the Pauli exclusion principle.

Therefore, since there are five orbitals in the d subshell and each can hold 2 electrons, the total capacity is calculated as follows:

5 orbitals × 2 electrons per orbital = 10 electrons.

This capacity accounts for all possible electron spins in each of the five orbitals, effectively utilizing the properties of quantum mechanics that govern electron behavior in atoms. The other choices either do not align with this fundamental understanding of electron configuration or do not account for the proper distribution in the d subshell.