Which of the following electronic configurations is not possible

Options

A. `1s^(2)2s^(2)`
B. `1s^(2)2s^(2)2p^(6)`
C. `3d^(10)4s^(2)4p^(2)`
D. `1s^(2)2s^(2)2p^(2)3s^(1)`

Answer

D

Explanation

When 2p orbital is completely filled then electron enters in the 3s. The capacity of 2p orbital containing `e^(-)` is 6. So `1s^(2),2s^(2)2p^(2)3s^(1)` is a wrong electronic configuration the right is `1s^(2)2s^(2)2p^(3)`.