A Sample Of Radioactive Material Has Mass 'm', Decay Constant Λ And Molecular Mass 'm'. If Na ​is Avogadro's Number, What Will Be The Initial Activity Of The Sample?


We know that the activity of any radioactive material is λN,


N is the number of undecayed nuclei at time t

λ is decay constant

We also know that N = N0e λt


N0 = number of undecayed nuclei at t = 0s

λ N0 = initial activity

N0 = \(\frac{m}{M} * N_{A}\)


m is the initial mass of the radioactive sample

M is the molecular mass of the sample.

NA is the avogadro number.

Therefore, the initial activity = \(\lambda \frac{mN_{A}}{M} \)

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