Question

Stable electronic configuration & unstable electronic configuration of Mg are :

• A. $1s^{2}2s^2{p}^{6}3s^2$ and $1s^{2}2s^2{p}^{6}3s^1{p}^1$
• B. $1s^{2}2s^2{p}^{6}3s^0{p}^2$ and $1s^{2}2s^2{p}^{6}3s^1{p}^1$
• C. $1s^{2}2s^2{p}^{6}3s^{1}4s^1$ and $1s^{2}2s^2{p}^{6}3s^1{p}^1$
• D. $1s^{2}2s^2{p}^{6}3s^1{p}^1$ and $1s^{2}2s^2{p}^{6}3s^1{p}^1$

Answer 1

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

Mg have 12 electrons and according to n+l rule its stable configuration is
$1s^{2}2s^2{p}^{6}3s^2$ and
any excited state of Mg will be unstable and have tendency to come to ground state so $1s^{2}2s^2{p}^{6}3s^1{p}^1$ is unstable.