Author Question: Bromine has two naturally occurring isotopes, Br-79 and Br-81. The mass of Br-79 is 78.92 u with a ... (Read 173 times)

MirandaLo · **on:** Nov 18, 2019

Question 1

Cerium has four stable isotopes listed below. If the weighted average atomic mass of cerium is 140.116 u, calculate the atomic mass of cerium-142.

Ce-136

135.90714 u

0.19%

Ce-138

137.90599 u

0.25%

Ce-140

139.90543 u

88.43%

Ce-142

11.13%

◦ 142.617 u
◦ 139.886 u
◦ 140.334 u
◦ 142.501 u
◦ 141.911 u

Question 2

Bromine has two naturally occurring isotopes, Br-79 and Br-81. The mass of Br-79 is 78.92 u with a percent abundance of 50.69%. If the atomic mass of bromine is 79.904 u, calculate the mass and percent abundance of Br-81.

◦ 80.028 u and 50.31%
◦ 78.921 u and 49.31%
◦ 80.916 u and 49.31%
◦ 80.916 u and 50.69%
◦ 79.904 u and 49.31%

frogdreck123456 · **Reply #1 on:** Nov 18, 2019

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