Physics

Problem

A laboratory has a sealed source containing

2.0\,\text{g}

^{226}\!\mathrm{Ra}

, whose half-life is

1.6\times10^{3}\,\text{yr}

. (Atomic mass of radium

=226\,\text{g mol}^{-1}

;

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

.) a. (i) Calculate the activity of the source at the present moment, expressing your answer in becquerel. b. (ii) Find the activity of the same source after

5.0\,\text{yr}

. c. (iii) Determine the percentage decrease in activity that occurs in this

5.0\,\text{yr}

interval.

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