Question

Elements $X,Y$ and $Z$ have atomic numbers 5, 9 and 11 respectively. Which one forms an anion?

• A. $X$
• B. $Y$
• C. $Z$
• D. Both $B$ and $C$

Answer 1

The correct option is B $Y$

Atomic number of$X$ is $5$ and electronic configuration is: $2,3$

Atomic number of $Y$ is $9$ and electronic configuration is: $2,7$

Atomic number of $Z$is $12$ and electronic configuration is: $2,8,1$

$Y$ is one electron short of stable completely filled configuration and thus readily accepts one electron to form an anion.