Consider the elements in the periodic table. The stair-step line between the pink squares and the yellow squares separates the _ (pink) from the _ (yellow).

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.

Sorry i dont understand the question can you rephase it?

Answer it is also known as the completion state is untrue of the activation complex;

Ithink ahopefully im correct