Define physical change in 4-5 sentences.

A physical change is any change in matter that involves the substance going from one physical state to another. The reference to a physical state involves solids, liquids, and gases. When a substance undergoes a physical change it does not lose its original properties when changing from one phase to another. The types of physical changes can vary. A substance can go from a solid to a liquid, a liquid to a gas, a gas to a liquid, a liquid to a solid, a solid to a gas, or a gas to a solid.

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.