Question

4
In the Hatom , what is the correct order (arrangement) of energy levels​

Answer 1

This is the correct order of energy levels 1s<2s=2p<3s=3p=3d<4s=4p=4d=4f<5s=5p=5d=5f

Answer 2

I believe you mean atom? 1s 2s 2p 3s 3p