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The half-life of Au 198 is 3 days. If atomic weight of Au 198 is 198 g mol - 1 , then the activity of 2 mg of Au 198 is [in disintegration second - 1 ]:

Options

  1. A2 . 67 × 10 12
  2. B6 . 06 × 10 18
  3. C32 . 36 × 10 12
  4. D16 . 18 × 10 12

Correct answer

D. 16 . 18 × 10 12

Step-by-step solution

A = λ N λ = ln 2 t 1 / 2 = ln 2 3 × 24 × 60 × 60   sec - 1 = 2 . 67 × 10 - 6   sec - 1 N = Number of atoms in 2   mg   Au = 2 × 10 - 3 198 × 6 × 10 23 = 6 . 06 × 10 15 A = λ N = 1 . 618 × 10 13 = 16 . 18 × 10 12   dps

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