Which of the following electron configurations of outer sublevels is the most stable?

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4d5 5s1 is where electron configurations of outer sublevels is the most stable. this could be a tricky question because of the fact the respond is going against the final rule that could say that 4d4 5s2 is the main sturdy. the final 2 a merely nonsence there is not any such factor as s3 or s4