Ignoring, for the moment, electron spin and electron-electron interaction, suppose that one electron in a helium atom is in the ground hydrogen-like state (0,0,0) and the other is in an excited state (un, l, (i) explain why w(r1, r2) = w0,0,0(r1)& n,1,mų (r2) is not a suitable wave function to describe the helium atom in this state. (ii) explain how this problem is overcome? (b) assume now that spin and electron-electron interaction are taken into account. all states of the atom can be classified as singlet states or triplet states. answer the following questions: (i) give a brief explanation of what distinguishes a singlet state from a triplet state. (ii) the singlet and triplet states of the same electron configuration have different energies. explain why. (iii) draw a schematic diagram showing the states for a helium atom for an electron configuration 1s2p, taking account of electron-electron interaction, exchange energy and spin-orbit coupling effects. spacings do not need to be to scale, but you should label the levels with relevant quantum numbers and spectroscopic notation. (iv) for the ground state electron configuration 1s”, explain why there is a singlet state only.