Question

Which of the following choices shows the ground state electron configuration of an ion of a halogen?

• A. $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$
• B. $1s^{2}2s^{2}2p^{6}3s^{2}3p^6$
• C. $1s^{2}2s^{2}2p^{6}2d^{10}3s^{2}3p^5$
• D. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}$

Answer 1

The correct option is A $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$

The halogens have outermost electronic configuration of $n{s}^{2}n{p}^5$. The d sub shell is not present in $2^{nd}$ orbit. Considering the $2$ points the ground state configuration of a halogen is present in option A.Hence answer is option A $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$