Question 1

Which of the following statements best explains why gamma rays are not deflected in a magnetic field, while alpha and beta rays are?

Accepted Answer

Gamma rays are neutral electromagnetic radiation, while alpha and beta rays are charged particles.

Question 2

A radioactive sample contains $$N_0$$ nuclei at time $$t=0. $$After a time equal to three half-lives, how many nuclei remain undecayed?

Accepted Answer

$$N_0/8$

Question 3

Which of the following best describes the process of beta-minus ($$\beta^-) $$decay?

Accepted Answer

A nucleus emits an electron and an antineutrino, converting a neutron into a proton.

Question 4

The half-life of Cesium-137 is 30 years. If a hospital stores a sample of Cs-137 for 90 years, what fraction of the original sample remains?

Accepted Answer

$$1/8$$

Question 5

Which of the following conservation laws is NOT violated in any type of radioactive decay?

Accepted Answer

All of the above are always conserved

Question 6

A sample of Iridium-192 (half-life = 73.8 days) is used in brachytherapy. If the initial activity is 1000 decays per second, what will the activity be after 221.4 days?

Accepted Answer

125 decays per second

Question 7

Which of the following statements about brachytherapy is correct?

Accepted Answer

It delivers high doses to tumors with rapid dose fall-off, sparing surrounding normal tissues.

Question 8

The mass of a carbon-12 atom is exactly 12 u. What is the energy equivalent of 1 u in MeV?

Accepted Answer

$$931.5$$ MeV

Question 9

Which isotope is most commonly used for high-dose-rate (HDR) afterloading brachytherapy in modern clinical practice?

Accepted Answer

Iridium-192

Question 10

A radioactive element emits 200 particles per second. After three hours, only 25 particles per second are emitted. What is the half-life of the element?

Accepted Answer

60 minutes

Question 11

Which of the following best describes the difference between the mass of a nucleus and the sum of the masses of its constituent protons and neutrons?

Accepted Answer

It is the binding energy of the nucleus.

Question 12

Which of the following is true regarding the penetration abilities of alpha, beta, and gamma radiation?

Accepted Answer

Beta rays can penetrate 3 mm of aluminum.

Question 13

The equation $$N = N_0$ e$$^{-\lambda t}$$ describes radioactive decay. What does $$\lambda$$ represent?

Accepted Answer

The decay constant, characteristic of the nuclide

Question 14

Which of the following is a correct example of alpha decay?

Accepted Answer

$$^{226}_{88}\mathrm{Ra} \$$rightarrow ^{222}$$_{86}\mathrm{Rn} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 15

Which property of radioactive decay makes it useful for radiometric dating (such as carbon dating)?

Accepted Answer

The decay rate is a random but statistically predictable process.

Question 16

What is the main advantage of using brachytherapy over external beam radiation therapy (EBRT) for treating tumors?

Accepted Answer

It delivers a high dose to the tumor with rapid dose fall-off, sparing normal tissues.

Question 17

Which of the following is the correct relationship between half-life $$T_{1/2}$$ and decay constant $$\lambda$$?

Accepted Answer

$$T_{1/2} = 0.693 / \lambda$$

Question 18

Which of the following statements about the strong and weak nuclear forces is correct?

Accepted Answer

The strong nuclear force holds nucleons together, while the weak nuclear force is responsible for beta decay.

Question 19

A sample of radium-226 has a half-life of 1600 years. What fraction of the original sample remains after 4800 years?

Accepted Answer

$$1/8$$

Question 20

Which of the following is a real-world application of the conservation of nucleon number?

Accepted Answer

Balancing nuclear equations during radioactive decay.

Nuclear Physics and Radioactivity – Study Notes (Phys 332, Chapter 30)

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