Question

1. The half-life of an isotope of phosphorus is 14.2 days. If a sample contains 3.96e16 such nuclei, determine its activity.?

2. A 234-mCi sample of a radioactive isotope is purchased by a medical supply house. If the sample has a half-life of 17.4 days, how long will it keep before its activity is reduced to 28.9 mCi?

Answer 1

Sao @ Activity of a huclear decay is defined by an) At N= humber of partives (Nuclei) =396x10 decay constant \1(2. Tuz half life. Given that half life = 14.2 days z Tua 852s Acitivity Un2 x 3.96 x 106 852 Activity = 2.60 x103 Bay =) Part-1) Given that activity (A.) Activity (A.) = 234mci Activity at any time (t) = 1-XNI putting N= Net A= XN. et AN. = Activity at t=0 (A) => A. Given that A=28.mai. 12 Inz = 1.4 days Iya -

ܗ ܐܬܠܝ .ܒ putting values 28.9mci ܪܫܝܡܢ-]ܛܗܝܿܡ254= ܦܝܘܐ ܦܝܒܢ ܛܝܒܢ t inz ܓܪܐ ܛ ܔܔܣܬ 5922.ܐ after t=52.5022 date actinity will become 28.9 mei.