A mixed radioactive sample contains of iodine-131 (half-life ) and of caesium-137…

PHYSICS · Multi-part · CBSE · Physics · Nuclei · Nuclei

Problem

A mixed radioactive sample contains

0.50\,\text{g}

of iodine-131 (half-life

8.0\,\text{d}

) and

0.50\,\text{g}

of caesium-137 (half-life

30\,\text{yr}

). (Atomic masses: iodine

=131\,\text{g mol}^{-1}

, caesium

=137\,\text{g mol}^{-1}

;

N_A = 6.02\times10^{23}\,\text{mol}^{-1}

.) (i) Calculate the initial activity contributed by each isotope separately. (ii) Determine the total activity of the sample after

24\,\text{d}

. (iii) What fraction of the total activity after

24\,\text{d}

is due to iodine-131?