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JAMB Chemistry 1990 Question 12

Question 12

Atomic Structure

Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5. The relative abundance of the isotope of mass number 37 is

  1. A.20
  2. B.25
  3. C.50
  4. D.75
Show the answer and explanation

Answer: B (25)

Explanation

Let x% be chlorine-37: 37x + 35(100 − x) = 3550, so 2x = 50 and x = 25%.