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Manipal MET2012ChemistryStructure of Atom

Which of the following has magic number of neutrons?

Options

  1. A₁₃ Al ²⁷
  2. B₂₆ Fe ⁵⁶
  3. C₈₃ Bi ²⁰⁹
  4. D₉₂ U²³⁸

Correct answer

C. ₈₃ Bi ²⁰⁹

Step-by-step solution

Magic numbers are 2,8,20,28,50 or 82 protons or 2,8,20,28,50,82 or 126 neutrons in the nucleus. These numbers impart stability to the nucleus. (a) ₁₃ Al ²⁷ , no. of neutrons =27-13=14 (b) ₂₆ Fe ⁵⁶ , no. of neutrons =56-26=30 (c) ₈₃ Bi ²⁰⁹ , no. of neutrons =209-83=126 (d) 92 U ²³⁸ , no. of neutrons =238-92=146

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