Question

What does the Aufbau principle state?
A. Electrons will be added to an atom in a random order.
B. Electrons will be added to an atom starting from the lowest possible level or sublevel.
C. Electrons will be added to an atom in a symmetrical manner.
D. Electrons will be added to an atom only if the orbitals are different colors.
E.Electrons will be added to an atom in order of their size.

Answer 1

Hello there!

The correct answer is B. Electrons will be added to an atom starting from the lowest possible level or sublevel.

Hope This Helps You!
Good Luck :) 

Answer 2

Answer: The correct answer is Option B.

Explanation:

Aufbau principle states that the electron will occupy the lowest energy level first before occupying the higher energy levels.

In filling of electrons, '1s' orbital will be filled first than '2s' orbital because the former has low energy level than the later.

For Example: Filling of electrons in chromium atom.

Chromium is the 24th element of the periodic table and its electronic configuration must be written as: $1s^22s^22p^63s^23p^63d^44s^2$

But the actual configuration for this is $1s^22s^22p^63s^23p^63d^54s^1$

This configuration is an exception to Aufbau's principle as half filled sub-levels is more stable than other configurations.

Hence, the correct answer is Option B.