The isotope lithium-7 has a mass of 7.0160 atomic mass units, and ...

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The isotope lithium-7 has a mass of 7.0160 atomic mass units, and the isotope lithium-6 has a mass of 6.0151 atomic mass units.
 
  Given the information that 92.58 percent of all lithium atoms found in nature are lithium-7 and 7.42 percent are lithium-6, calculate the atomic mass of lithium, Li (atomic number 3).
  A) 7.0160 amu
  B) 6.942 amu
  C) 6.495 amu
  D) 13.031 amu

Question 2

The American Chemistry Council is ________.
 
  A) a society of chemistry educators
  B) a special interest group
  C) an organization of environmental lawyers
  D) an advisory panel to the U.S. Congress

[wergv]

Answer to Question 1

B

Answer to Question 2

B

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Thank you!

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Always glad to help...