Question

The electronic configuration of a p-block element is ${\text{[He]2s}}^2{\text{2p}}^5$. The group number of this element is:

• A. 17

Answer 1

The correct option is A 17
Elements in which the last electron enters the outermost p-subshell are called p-block elements. They are present in the groups 13 to 18 of the modern periodic table.

For p-block elements, the group number can be obtained by adding 12 to the total number of electrons present in the outermost p-subshell. Since, ${\text{[He]2s}}^2{\text{2p}}^5$ has five electrons in its outermost p-subshell (2p), its group number is 17 (12+5).