InterviewSolution
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InterviewSolution
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(a) Define the term activity of a sample of radioactive nucleus. Write its SI unit. (b) The half-life of " "_(92)^(238)U undergoing alpha-decay is 4.5 xx 10^(9) years. Determine the activity of 10 g sample of " "_(92)^(238)U. Given that 1 g of " "_(92)^(238)U contains 25.3 xx 10^(20) atoms. |
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Answer» Solution : (b) Here `T_(1/2)=4.5 xx 10^(9) years = (4.5 xx 10^(9)) xx (3.154 xx 10^(7)) s`, mass of `" "_(92)^(238)U` (m) = 10 G and number of ATOMS per gram `= 25.3 xx 10^(20)`. `therefore` Total number of atoms in given sample `N = 10 xx 25.3 xx 10^(20) = 2.5 xx 10^(22)` `therefore` Activity `R= (-(DN)/(dt))=lambdaN=0.693/T_(1/2)=(0.693xx(2.53xx10^(22)))/(4.5xx10^(9)xx3.154xx10^(7))=1.235xx5s^(-1)=1.235xx10^(5)Bq` |
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