Question

Which of the following electronic configuration is incorrect?

• A. P = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$
• B. Q = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^1$
• C. R = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}3d^5$
• D. S = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$

Answer 1

The correct option is C R = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}3d^5$

The electrons are filled in the order of subshells with lower energy to those of higher energy.


Therefore, the electronic configuration of R is wrong because only after 6 electrons fill the 3p subshell, the 4s and 3d subshell will be filled.