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A piece of radioactive material contains 1020 atoms. If the half life of the material ...

A piece of radioactive material contains 1020 atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is
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  • A 3.47 x 1018
  • B 6.93 x 10 20
  • C 3.47 x 1020
  • D 6.93 x 1018
Correct Answer: Option A
Explanation:
The number of disintegration,∆N in time interval At, is given by
- ∆N = N∆t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T
∴ ∆N = (0.693)/1(1)/2 N∆t = (0.693 x 10)20 x 10/20 = 3.47 x 1018

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