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A nucleus of `Ux_1` has a half life of 24.1 days. How long a sample of `Ux_1` will take to change to 90% of `Ux_1`.A. 80 daysB. 40 daysC. 20 daysD. 10 days |
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Answer» Correct Answer - a Here, `lambda=0.693/(T_(1//2)) =0.693/24.1=0.02876 "day"^(-1)` `N=N_0-90%` of `N_0 = N_0/10` As N=`N_0e^(-lambdat)` `therefore N_0/10=N_0e^(-lambdat)` or `1/10 = e^(-lambdat)` or `10=e^(lambdat)` or `log_e10= lambdat` `therefore t=1/lambda_"log"_e 10=(2.303 log 10)/0.02870 = (2.303xx1)/0.02876 `= 80 days |
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