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?