Question

According to Aufbau principle, the correct order of energy of 3d, 4s and 4p-orbitals is :

• A. $4p<3d<4s$
• B. $4s<4p<3d$
• C. $4s<3d<4p$
• D. $3d<4s<4p$

Answer 1

Answer: (C)

$4s<3d<4p$

Aufbau principle states that electron enters the orbital of lowest energy first and subsequent electrons are filled in the order of increasing energies.

According to Aufbau principle, option $C$ is in the correct order.