Question
  1. Define ‘activity’ of a radioactive material and write its $S.I.$ unit.
  2. Plot a graph showing variation of activity of a given radioactive sample with time.
  3. The sequence of stepwise decay of a radioactive nucleus is

If the atomic number and mass number of $D_2$ are $71$ and $176$ respectively, what are their corresponding values for $D$?

Answer

  1. The total decay rate $($of a sample$)$ at the given instant, i.e., the number of radionuclides disintegrating per unit time is called the activity of that sample. The $SI$ unit for activity is becquerel $(Bq)$.
  2. Graph:
  1. $72$ and $180$.

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