28. An electron in a hydrogen atom is excited from the ground state to the n = 4 state. Comment on the cor- rectness of the following statements (true or false). (a) n = 4 is the first excited state. (b) It takes more energy to ionize (remove) the electron from n = 4 than from the ground state. (c) The electron is farther from the nucleus (on average) in n = 4 than in the ground state. (d) The wavelength of light emitted when the electron drops from n = 4 to n = 1 is longer than that from n = 4 to n = 2. (e) The wavelength the atom absorbs in going from n = 1 to n = 4 is the same as that emitted as it goes from n = 4 to n = 1. 29. The ionization energy of a certain element is 412 kJ/mol (see Problem 7.119). However, when the atoms of this element are in the first excited state, the ionization en- ergy is only 126 kJ/mol. Based on this information, calculate the wavelength of light emitted in a transition from the first excited state to the ground state. 30. Alveoli are the tiny sacs of air in the lungs (see Prob- lem 5.132) whose average diameter is 5.0 × 105 m. Consider an oxygen molecule (5.3 × 10-26 kg) trapped within a sac. Calculate the uncertainty in the velocity of the oxygen molecule. (Hint: The maximum uncer- tainty in the position of the molecule is given by the diameter of the sac.) 31. How many photons at 660 nm must be absorbed to melt 5.0 × 102 g of ice? On average, how many H₂O molecules does one photon convert from ice to water? (Hint: It takes 334 J to melt 1 g of ice at 0°C.) 32. Shown below are portions of orbital diagrams repre- senting the ground-state electron configurations of certain elements. Which of them violate the Pauli ex- clusion principle? Hund's rule? (a) 个人↓ (b) (c) (d) (f) (e)