Question

Which of the subshells in the electron configuration of hf behave as core orbitals?

Answer 1

Of all the sub-shells shown ( 1s ,2s ,2p ,3s ,3p ,4s ,3d ,4p ,5s ,4d ,5p ,6s ,4f ,5d) the ones that act as core orbital of HF (Hydrogen Fluoride) is 6s and 5d