Which one of the following statements about the exchange energy of the few lowest excited states of helium, in which the two electrons are in different subshells, is incorrect? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer.
a. In the absence of the exchange energy, the degeneracy between 1s¹2s¹ and 1s¹2p¹ configurations would only be lifted by relativistic corrections.
b. For a given configuration and L the exchange energy favours (ie the energy is lower for) S=1 compared with S=0
c. For a given configuration and L the exchange energy favours states that are spatially anti-symmetric
d. The exchange energy gives larger shifts in the levels than relativistic corrections