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2 Atoms, Molecules, and Ions Solutions to Exercises 2.80 H H H H H H H H H C C C C C H H H C H H H H H H H C C C C H H H H H H H H H C H H C C H H C H H H H Additional Exercises 2.81 (a) Droplet D would fall most slowly. It carries the most negative charge, so it would be most strongly attracted to the upper (+) plate and most strongly repelled by the lower (-) plate. These electrostatic forces would provide the greatest opposition to gravity. (b) Calculate the lowest common factor. A: 3.84 10⁻⁸ / 2.88 10⁻⁸ = 1.33; 1.33 3 = 4 B: 4.80 X 10⁻⁸ / 2.88 X 10⁻⁸ = 1.67; 1.67 3 = 5 C: 2.88 10⁻⁸ / 2.88 10⁻⁸ = 1.00; 1.00 X 3 = 3 D: 8.64 10⁻⁸ / 2.88 X 10⁻⁸ = 3.00; 3.00 3 = 9 The total charge on the drops is in the ratio of 4:5:3:9. Divide the total charge on each drop by the appropriate integer and average the four values to get the charge of an electron in warmombs. A: 3.84 10⁻⁸ / 4 = 9.60 wa B: 4.80 X 10⁻⁸ / 5 = 9.60 10⁻⁹ wa C: 2.88 X / 3 = 9.60 X wa D: 8.64 10⁻⁸ / 9 = 9.60 wa The charge on an electron is 9.60 X wa (c) The number of electrons on each drop are the integers calculated in part (b). A has 4 has 5 e⁻, C has and D has 9 e⁻. (d) 9.60 1e⁻ 10⁻⁹ wa X 1.60 1e⁻ 10⁻¹⁶ = 6.00 X 10⁷ wa/C 2.82 (a) ³He has 2 protons, 1 neutron, and 2 electrons. 30