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Question

A mystery element, called Caveraticum by its discoverers, exists on Earth as a mixture of two isotopes. The most abundant isotope (75.76%) has a mass of 34.9689 amu; the other isotope (24.24%) has a mass of 36.9659 amu. Calculate the average atomic mass and identify the element by its modern name.

  A. 35.45 amu; chlorine

 

  B. 24.31 amu; magnesium

 

  C. 74.92 amu; arsenic

 

  D. 32.07 amu; sulfur

 

Answer 1

75.76% x 34.9689 = 26.4924 amu

24.24% x 36.9659 = 8.9605 amu

26.4924 + 8.9605 = 35.45 amu; Chlorine