Review Questions

1 . Element  is formed  as  a   result  of  3   α   and  2   β– decays. Which   of  the following   is  the

parent  element?

(A)

(B)

(C)

(D)

2 . Element X   is  radioactive and decays  via α   decay   with    a   half-life   of  4   days.   If  12.5%   of  an

original    sample  of  element X   remains after   N days, determine   N.

    days

3 . A   patient undergoing  treatment   for thyroid cancer  receives    a   dose    of  radioactive iodine

(^131 I),   which   has a   half-life   of  8.05    days.   If  the original    dose    contained   12  mg  of  ^131 I, what

mass    of  ^131 I  remains after   16.1    days?

    mg

4 . In  an  exponential decay,  if  the natural logarithm   of  the ratio   of  intact  nuclei  (n) at  time    t   to

the intact  nuclei  at  time    t   =   0   (n 0 )  is  plotted against time,   what    does    the slope   of  the graph

correspond  to?