Question 1

Which subatomic particle is responsible for the unique identity of an element, and how is this reflected in the periodic table?

Accepted Answer

The proton; its number is shown as the atomic number above the element symbol.

Question 2

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it contain?

Accepted Answer

16

Question 3

Which statement best describes isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 4

Which type of nuclear radiation has the greatest penetrating power and requires thick concrete or lead for shielding?

Accepted Answer

Gamma rays

Question 5

A radioactive isotope has a half-life of 4 days. If you start with 80 mg, how much remains after 12 days?

Accepted Answer

10 mg

Question 6

Which nuclear equation correctly represents the alpha decay of uranium-238?

Accepted Answer

$^{238}_{92}U \rightarrow ^{234}_{90}Th + ^{4}_{2}He$

Question 7

Which of the following is a correct symbolic notation for an atom of carbon with 7 neutrons?

Accepted Answer

$^{13}_{6}C$

Question 8

What is the SI unit for measuring the biological effect of radiation exposure?

Accepted Answer

Sievert (Sv)

Question 9

Which statement best explains why radioisotopes used in medical imaging should have short half-lives?

Accepted Answer

Short half-lives allow for rapid elimination of radioactivity, minimizing patient exposure.

Question 10

Which of the following describes the process of beta decay?

Accepted Answer

A neutron is converted into a proton and an electron is emitted.

Question 11

A sample of iodine-131 (half-life = 8 days) is used to treat thyroid cancer. If a patient receives 32 mg, how much remains after 24 days?

Accepted Answer

4 mg

Question 12

Which type of radiation is most likely to cause damage to rapidly dividing cells, such as those found in cancerous tissue?

Accepted Answer

Ionizing radiation

Question 13

Which of the following is true about the mass of subatomic particles?

Accepted Answer

Protons and neutrons each have a mass of approximately 1 amu.

Question 14

Which of the following nuclear equations represents positron emission?

Accepted Answer

$^{18}_{9}F \rightarrow ^{18}_{8}O + ^{0}_{+1}e$

Question 15

A PET scan uses fluorine-18, which decays by positron emission. What happens when the emitted positron encounters an electron?

Accepted Answer

They annihilate each other, producing gamma rays.

Question 16

Which of the following is NOT a form of ionizing radiation?

Accepted Answer

Visible light

Question 17

If a stable isotope is bombarded with a neutron, which side of the nuclear equation will the neutron appear?

Accepted Answer

On the reactant side

Question 18

Which of the following best describes the difference between atomic mass and mass number?

Accepted Answer

Atomic mass is the weighted average of all isotopes, while mass number is the sum of protons and neutrons in a single atom.

Question 19

Which shielding material is most effective against alpha particles?

Accepted Answer

Paper or clothing

Atoms and Radioactivity: Structure, Properties, and Applications

Study Guide - Practice Questions