Question

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

Explanation:

Noble - gas notation uses the noble - gas core that comes before the element. Elements with valence electrons in the 5s subshell start after krypton (Kr). Krypton has a complete electron configuration up to the 4p subshell. The next elements start filling the 5s subshell. So, Kr is used as the noble - gas core in their noble - gas notation.

Answer:

B. Kr