Question

Tc-99 is a radioactive isotope that decays by beta emission and is used by radiologists in the diagnosis of liver disease. Its decay behavior is shown by the activity-time table. What is its half-life?

Answer 1

You are supposed to look at the table and use the data to calculate the half life. How do you suppose we can do that if you don't show the table?

Answer 2

The table wasn't available

Answer 3

counts/min time(hours)
800 0
713 1
450 5
200 12
112 17
a. 5h
b. 6h
c. 12h
d. 99h

Answer 4

ln(No/N) = kt
No = 800 in all cases.
N = values from table
k = solve for this
t = time in hours.
For example, the first one is
ln(800/713) = k(1 hour)
k = 0.115 if I didn't goof.
Do that for each time period and average the values. Then substitute into the following:
k = 0.693/t_1/2 and solve for t_1/2.