Question

Be sure to answer all parts. 90Sr.( The half-life of strontium-90 is 29.1 years. Calculate the radioactivity in millicuries of 16.4 mg of 90Sr = 89.908 g/mol) Enter your answer in scientific notation. X 10! mCi

Answer 1

Half life The time the radioactive sample takes to reduard in its gets decayed to half of its initial amount radioactivity formula. --kt No where K-decay const- NE = o mau of radioactive materal at time t! No= Onitial mous = IN en (Nt ) UK at so, half life, tity and N+= nome No so, en 1N% akty NO 少 -K* 29.1 years * K= 0,0232 en (1) 0.02.12 year! sample intal weight = 16.4 mg. 90so, m. W = 89.90g/mol moles of so inihaly present= 16.4 x 10 g 90 89.90 Noma = 0.1824 xlo mol 1 mol containe 6.023x10 most estabes atomi o 1824 x 103 mole contains = 1.098 8 10 magsaber a formy 21 6.023 X 10 X 0_1824 X10 20

KXN K-decay Activity conet N = no. of atome present radioactivity 0.0 2.32 x yearé' x 1.098 xido atoma 0.0255 atoms year - 0.0255 atoms box1365 x 24x60X60) sec. 8.08 81010 So, their radioactivity 8.06 X1ālo * 8.06 X1ūlo diziontegration pour des 1 millicurie = 3.7 x 107 diasn't disintegration persee drintegration per second atoms/ sec. so, 8.08 81010 *8.08x1080 3.7x107 2,18 x 1017 mai so, |2, 18 x 10 t mc mail