Q38 / 199 · NTA Abhyas (NEET) 2020 · Physics · Nuclear Physics

In a radioactive disintegration, the ratio of the initial number of atoms to the number of atoms present at an instant of time equal to its mean life is

  • A
    1e2
  • B
    1e
  • Correct answer
    C
    e
  • D
    e2

Solution

Let the initial number of atoms at time t=0 be N0.

Let N be the number of atoms at any instant t.

Mean life τ=1λ , where λ is disintegration constant.

Given , t= τ

According to radioactive disintegration law,

            N=N0e-λt

or       N=N0e-λ × 1λ = N0e

 or     N0N = e

Hence, the correct answer is option: 'C'.

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