Question

An element $X$ belongs to $3^{rd}$ period and ${17}^{th}$ group, state
(i) no. of valence electrons in it.

Answer 1

The element present in the $3^{rd}$ period and ${17}^{th}$ group is chlorine, and it possesses 7 electrons in its valence shell.

As Valence electrons = Group $-10$

Thus, the number of valence electrons in element $X$ will be $7$.