Which of the following symbols would be included in the noble gas notation for an element that had valence electrons in the 5s subshell?

Ar

Kr

Xe

Rn

The answer will come in handy when you have a periodic table. The electron configuration, 5s, means that the element, which in this case is a noble gas, is in the fifth row. From the given noble gases, the one on the fifth row is xenon (Xe). Thus, the answer is the third choice.