The electron in a hydrogen atom can undergo a transition from n=4 to n=3, emitting a photon with energy 1.06 x 10-19 j. use this transition to answer the following questions

They are all decomposition reactions.

The answer is letter 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.