In a chemical equation, what do the coefficients indicate?

In a chemical equation coefficients indicate the number of molecules/atoms involved in the reaction.

Olá. porque a reação na temperatura é muito rapida a do copo : )

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.