Final answer:
The electronic configuration of an atom of X is [Ar] 4s²3d¹04p5.
Step-by-step explanation:
The electronic configuration of an atom of X, which has the same configuration as the ion X2+ and the atom Kr, is [Ar] 4s²3d¹04p5. The notation [Ar] represents the electronic configuration of the noble gas Argon (Kr is a noble gas too), indicating that the electron configuration of X is the same as that of Argon up until its 18 electrons. The remaining electrons follow the pattern of 4s²3d¹04p5.
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