HW: Percent Abundance of Isotopes

The element indium has two common isotopes: indium-113 (112.90406 amu) and indium-115 (114.90388 amu). If the average atomic mass of indium is 114.818 amu, what are the percent isotopic abundances of indium-113 and indium-115?

• Indium-113: 4.3%

  Indium-115: 95.7%

• Indium-113: 95.7%

  Indium-115: 4.3%

• Indium-113: 50.0%

  Indium-115: 50.0%

• Indium-113: 25.0%

  Indium-115: 75.0%

Tags

NGSS.HS-PS1-8

NGSS.HS-PS1-7

The element europium has two naturally-occurring isotopes: europium-151 (150.91985 amu) and europium-153 (152.92123 amu). If the average atomic mass of europium is 151.964 amu, what are the percent isotopic abundances of europium-151 and europium-153?

• 47.8% Europium-151

  52.2% Europium-153

• 52.2% Europium-151

  47.8% Europium-153

• 50.0% Europium-151

  50.0% Europium-153

• 48.0% Europium-151

  52.0% Europium-153

Tags

NGSS.HS-PS1-8

The element lutetium has two common isotopes: lutetium-175 (174.94077 amu) and lutetium-176 (175.94268 amu). If the average atomic mass of lutetium is 174.967 amu, what are the percent isotopic abundances of lutetium-175 and lutetium-176?

• Lutetium-175: 97.4%

  Lutetium-176: 2.6%

• Lutetium-175: 50.0%

  Lutetium-176: 50.0%

• Lutetium-175: 75.0%

  Lutetium-176: 25.0%

• Lutetium-175: 2.6%

  Lutetium-176: 97.4%

The element lithium has two common isotopes: lithium-6 (6.0151223 amu) and lithium-7 (7.016004 amu). If the average atomic mass of lithium is 6.94004 amu, what are the percent isotopic abundances of lithium-6 and lithium-7?

• Lithium-6: 7.59%

  Lithium-7: 92.41%

• Lithium-6: 50%

  Lithium-7: 50%

• Lithium-6: 92.41%

  Lithium-7: 7.59%

• Lithium-6: 25%

  Lithium-7: 75%

The element bromine has two common isotopes: bromine-79 (78.918 amu) and bromine-81 (80.916 amu). If the average atomic mass of bromine is 79.9 amu, what are the percent isotopic abundances of of each isotope?

• bromine-79: 50.85%

  bromine-81: 49.15%

• bromine-79: 50.9%

  bromine-81: 49.1%

• bromine-79: 92.41%

  bromine-81: 7.59%

• bromine-79: 25.0%

  bromine-81: 75.0%