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Consider ""^(228)Th overset(-alpha)rarr ""^(224)Ra overset(-alpha)rarr ""^(220)Rn where t_((1)/(2)) (""^(228)Th)=1.913 yr, t_((1)/(2)) (""^(224)Ra)=3.64d. Determine the N (Th)/N (Ra) ratio once transient equilibrium in which t_((1)/(2)) (parent) gt t_((1)/(2)) (daughter) or lamda (parent) lt lamda (daughter) has been established |
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Answer» Solution :We have, `(N_(1))/(N_(2))= (lamda_(2)-lamda_(1))/(lamda_(1))` Now, `lamda_(1)= (0.6932)/((t_((1)/(2)))_(1))= (0.6932)/(1.913 xx 365)=9.927 xx 10^(-4) d^(-1)` `lamda_(2)= (0.6932)/((t_((1)/(2)))_(2))= (0.6932)/(3.64)= 0.1900 d^(-1)` Thus, `(N(Th))/(N(RA))= (0.1900-9.927 xx 10^(-4))/(9.927 xx 10^(-4))= 190` |
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