which of the following is not true of molecular orbitals? a) the number of molecular orbitals formed is always equal to the number of atomic orbitals combined. b) a molecular orbital can accommodate up to two electrons. c) when electrons are added to orbitals of the same energy, the most stable arrangement is predicted by hund's rule. d) low-energy molecular orbitals fill before high-energy molecular orbitals fill. e) for any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms.