Identify each of the following catalysts as homogeneous or heterogeneous.

The addition of a strip of solid platinum metal to an aqueous solution of hydrogen peroxide increases the reaction rate of the decomposition reaction:

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.

I'm sorry but i'm only grade