Question

The element $X$ has the electronic configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^5$. $X$ belongs to :

• A. $4^{th}$ period, VA group
• B. $5^{th}$ period, IVA group
• C. $4^{th}$ period, VIIA group
• D. $7^{th}$ period, IVA group

Answer 1

The correct option is C $4^{th}$ period, VIIA group

Valence electrons indicate group number and valence shell indicates the period number.

$4s^{2}4p^5$ is the valency shell configuration, i.e., 7 electrons in the valence shell which indicates that this element belongs to the 17th group, i.e., VIIA. And $n=4$, that means it belongs to the $4^{th}$ period.

Hence, option C is correct answer.