[Kr]5s24d1 would be Yttrium, If I remember correctly.
Kr5s2 is the electron configuration for the element krypton. This notation indicates that there are 5 electrons in the 4th energy level (K shell) and 2 electrons in the 5th energy level (L shell) of a krypton atom.
The electron configuration of the element Strontium, or Sr.. 5s2 being the 5th spherical orbital, with 2 electrons..as for the [kr], Idk