Final answer:
The element whose 2+ ion has the electron configuration [Kr]5s0 4d10 is Zinc (Zn). When Zn loses two electrons to form Zn2+, it attains this configuration.
Step-by-step explanation:
The student's question is about finding which element's 2+ ion has the electron configuration [Kr]5s04d10. In order to identify the element, we need to consider a neutral atom that would have two more electrons than the given configuration, as those two electrons would be the ones lost to form the 2+ ion. The electron configuration of the neutral atom would be [Kr]5s24d10, which is the configuration for the element Zinc (Zn). Therefore, when Zinc loses two electrons to form Zn2+, it will have the configuration [Kr]5s04d10, making Zinc the correct answer to the student's question.