Solid substance A has a melting point of 100°C. Liquid substance B has a freezing point of 110°C. For each substance, identify its state of matter and describe the motion of its particles when the substance is at 115°C.

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.