_____1. A vial contains 100 mCi of an unidentified radionuclide at 10am Thursday. At 10am Friday, the activity has decayed to 25 mCi. What is the half-life of the unidentified radionuclide?

a. 24 hrs

b. 12 hrs

c. 6 hrs

d. 4 hrs

e. 100 hrs

 

_____2. P-32 has a t_1/2 of 14.3 days. A sample has an original activity of 200 mCi. How much will be left after 3 days?

a. 173 mCi

b. 175 mCi

c. 179 mCi

d. 184 mCi

 

_____3. O-15 has a decay constant of 0.335 min^-1. How much of a 15 mCi sample of O-15 will remain after 5 minutes?

a. 1.5 mCi

b. 2.8 mCi

c. 4.2 mCi

d. 5.6 mCi

 

_____4. In-113m has a decay constant of 0.0069 min^-1 . What will be the activity in microCi of a 20 milliCi sample after 24 hrs?

_____5. F-18 has a decay constant of 0.0063 min^-1. What percentage of a sample will be left after 2 hours?

a. 35%

b. 38%

c. 47%

d. 52%

 

_____6. I-123 has a half-life of 13 hours. A sample of the material has an activity of 5.6 mCi at noon today. What was its activity at noon yesterday?

a. 10 mCi

b. 15 mCi

c. 20 mCi

d. 25 mCi

 

_____8. If I-131 compound has a t_biol of 24 days and T_phys = 8 days, what is the mean effective half-life?

a. 8 days

b. 6 days

c. 8.7 days

d. 24 days

 

_____9. For a T_phys = 46 days and a T_eff = 14 days. What is T_biol?

a. 32 days

b. 60 days

c. 15.94 days

d. 20.12 days

 

_____10. Answer True/False

a. Tc99m decays by internal conversion to Tc-99g.

b. Beta plus decay competes with Beta minus decay in many nuclides.

c. Internal conversion electrons emitted from inside an internal organ lose approximately 10% of their energy in that organ.

d. Tc-99g (t_1/2 = 2X10⁵ yr) has been discovered in Siberian mineral deposits.