The activity of a freshly prepared radioactive sample is 10¹⁰ disintegrations per second, whose mean life is 10⁻⁹ ~s . The mass of an atom of this radioisotope is 10⁻²⁵ ~kg . The mass (in mg ) of the radioactive sample is

Step-by-step solution

Activity (- d N d t )= N= ( 1 t_ mean ) N aligned & N= (- d N d t ) t_ mean & = Total number of atoms & Mass of one atom is 10⁻²⁵ ~kg =m (say) & Total mass of radioactive substance & =( number of atoms) & ( mass of one atom) & = (- d N d t ) (t_ mean )(m) aligned Substituting the values, we get Total mass of radioactive substance =1 mg Answer is 1 . Analysis of Question Question is very simple. Again in my opinion one can solve it.