# Radioactive Decay Concept Questions

13. Which one of the following can be done to shorten the half life of the radioactive decay of uranium-238?

a. Oxidize it to the +2 oxidation state.

b. Heat it.

c. Freeze it.

d. Convert it to UF6.

e. None of these

14. The half-life for beta decay of strontium-90 is 28.8 years. A milk sample is found to contain 10.3 ppm strontium-90. How many years would pass before the strontium-90 concentration would drop to 1.0 ppm?

a. 131

b. 0.112

c. 92.3

d. 186

e. 96.9

15. The decay of a radionuclide with a half-life of 4.3 x 105 years has a rate constant (in yr-1) equal to ________.

a. 6.2 x 105

b. 5.9 x 10-8

c. 2.8 x 103

d. 2.3 x 10-6

e. 1.6 x 10-6

16. Consider the following data for a particular radionuclide:

Time Nt

0 min 1.23 g

3 1.15

6 1.08

9 1.01

12 0.940

What is the half-life (in min) of this radionuclide?

a. 30.9

b. 0.0242

c. 0.0224

d. 0.0324

e. 44.64

17. The mass of a proton is 1.673 x 10-24 g. The mass of a neutron is 1.675 x 10-24 g. The mass of the nucleus of an 56Fe atom is 9.289 x 10-23 g. What is the nuclear binding energy (in J) for Fe56?

(C = 3.00 x 108 m/s)

a. 7.72 x 10-8

b. 7.72 x 10-11

c. 6.07 x 106

d. 2.57 x 10-16

e. 8.36 x 10-9

#### Solution Preview

13. Which one of the following can be done to shorten the half life of the radioactive decay of uranium-238?

e. None of these

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14. The half-life for beta decay of strontium-90 is 28.8 years. A milk sample is found to contain 10.3 ppm strontium-90. How many years would pass before the strontium-90 concentration would drop to 1.0 ppm?

log (co/ct) = kt/2.303

where co is the initial amount and ct is the amount remaining at time t.

But first, we have to calculate k, the rate ...

#### Solution Summary

This solution contains explanations and calculations to determine the right answer for the radioactive decay questions.