Question

In the given elements, which element does not have 2 valence electrons?

• A. Ba
• B. Zn
• C. Na
• D. Ca

Answer 1

The correct option is C Na

Electronic configuration of Ba - [Xe], 6s${}^2$.
Electronic configuration of Zn - [Ar], 3d${}^{10}$, 4s${}^2$.
Electronic configuration of Na - [Ne], 3s${}^1$.
Electronic configuration of Ca - [Ar], 4s${}^2$.

In the above choices, Na contains only 1 valence electron.

Hence, option (C) is the correct answer.