9/6 Concept Test Questions
1. Thomson obtained a value of -1.759 x 1011 C/kg (Coulombs/kilogram) for the charge-to-mass (e/m) ratio for the electron. Millikan determined the charge (e) on the electron to be -1.602 x 10-19 C. Calculate the mass of an electron.
A) 1.098 x 1030 kg
B) 9.107 x 10-31 kg
C) 2.817 x 10-8 kg
2. The two major isotopes of bromine are 79Br and 81Br. Assume that the masses of the 79Br and 81Br isotopes are 79.00 and 81.00 amu, respectively. The weighted average atomic mass of bromine is 79.90. What are the relative % abundances of each isotope? Estimate WITHOUT detailed calculations!
% Abundance of 79Br |
% Abundance of 81Br |
|
A) |
79.0% |
21.0% |
B) |
19.0% |
81.0% |
C) |
35.1% |
64.9% |
D) |
55.0% |
45.0% |