Aufbau principle is obeyed in which of the following electronic configuration

Options

A. `1s^2 2s^2 2p^6`
B. `1s^2 3p^3 3s^2`
C. `1s^2 3s^2 3p^6`
D. `1s^2 2s^2 3s^2`

Answer

A

Explanation

According to Aufbau principle electron are filling increasing order of energy. Therefore the electronic configuration `1s^2 2s^2 2p^6` obeys Aufbau principle