Question

Suppose that a certain radioactive element decays in such a way that every twenty years the mass of a sample of the element is one third of the initial mass. Given a 100 gram sample of the element, how much of the element remains after 17 years?

Answer 1

' Solution using Radio active decay formula N = no elt , Mos initial amount ,N= Renaaing x = decay constant amount Giren Mo=100 gm at t=20 year N= No so, o = No e 120 Śre 201 Take matural log both side en (43) = -201 A = 1 en (4/3) Ha No et eo en (4/3). & How we find N at t = 17 years M= Loo e tha en (4/3). 17 N=1c0 et ln(43).47 IN= 39.30 gm.