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A radioactive sample at some instant has a disintegration rate of 5000 disintegrations per minute. After 5 minutes, the rate becomes 1250 disintegrations per minute. Then, the decay constant (per minute) is

Options

  1. A0.4 ln 2
  2. B0.2 ln 2
  3. C0.1 ln 2
  4. D0.8 ln 2

Correct answer

A. 0.4 ln 2

Step-by-step solution

A A 0 = 1 2 5 0 5 0 0 0 = 1 4 = 1 2 t T ⇒ T = t 2 = 5   2 λ = ln 2 T = 2 5 l n 2 = 0.4   ln 2

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