Question

The orbital diagram in which Aufbau principle is violated, is:

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Option (b) is wrong according to Aufbau principle. A higher energy atomic orbital $2p$ cannot be filled unless the lower energy orbital $2s$ is completely occupied.
In case of option (a), aufbau principle is not violated as electrons get filled in the $2p$ after the filling of lower orbital $2s$. Option (c) and (d) obey Aufbau principle.