Question

An element $X$ forms a unipositive ion with the electronic structure $2,8,8$. What is the atomic number of $X$?

• A. $16$
• B. $17$
• C. $18$
• D. $19$

Answer 1

The correct option is D $19$

Unipositive ion means it loose one electron so $2,8,8,1=19$, hence $X$ is potassium $19$.