The half-life of Au198 is 2.7 days. The activity of 1.50 mg of Au198 if its atomic weight is 198 g mol$-$1 is, (Na = 6 $\times$ 1023/mol).
Solution
Activity, $A = \lambda N$<br><br>Where, $N = n{N_A}$<br><br>${N_A} = 6 \times {10^{23}}$/mol<br><br>$= {{6 \times {{10}^{23}}} \over {3.7 \times {{10}^{10}}}}$ Ci<br><br>Here, ${A_0} = \lambda {N_0}$<br><br>We know, <br><br>${T_{1/2}} = {{\ln (2)} \over \lambda }$<br><br>$\Rightarrow \lambda = {{\ln (2)} \over {{T_{1/2}}}}$<br><br>$= {{\ln (2)} \over {2.7 \times 3600 \times 24}}$<br><br>$\therefore$ ${A_0} = {{\ln (2)} \over {2.7 \times 3600 \times 24}} \times$ $n \times {N_A}$<br><br>$$ = {{\ln (2)} \over {2.7 \times 3600 \times 24}} \times {{1.5 \times {{10}^{ - 3}}} \over {198}} \times {{6 \times {{10}^{23}}} \over {3.7 \times {{10}^{10}}}}$$<br><br>$= 366$ Ci<br><br>$\therefore$ Nearest answer is 357 Ci.
About this question
Subject: Physics · Chapter: Atoms and Nuclei · Topic: Bohr's Model of Hydrogen Atom
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