"Indicate which element or elements have the electron characteristics below. In those cases where a series of elements have the indicated characteristics don't write all the symbols but rather write the atomic numbers of the first and last elements in the series.
(c) Two 7s electrons (note that more than one element qualifies)"
My answer: 88-118 (Those are all the elements to the right of 7s)
Book's answer 88-112.
Question: what doesn't the book include elements 113-115? They are listed in peridic table even though they are unnamed, and they would still have two 7s electrons.