Question 1

Which subatomic particle is responsible for the unique identity of an element, and where is it located in the atom?

Accepted Answer

Proton; in the nucleus

Question 2

What is the mass number of an atom with 17 protons, 18 neutrons, and 17 electrons?

Accepted Answer

$$35$$

Question 3

Which of the following statements best describes isotopes?

Accepted Answer

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

Question 4

A radioactive isotope decays by emitting a beta particle. What happens to the atomic number and mass number of the resulting atom?

Accepted Answer

Atomic number increases by 1; mass number stays the same.

Question 5

Which type of radiation has the greatest penetrating power and is most likely to require lead shielding for protection?

Accepted Answer

Gamma rays

Question 6

A sample of iodine-131 (half-life = 8 days) is used in a medical procedure. If you start with 40 mg, how much remains after 24 days?

Accepted Answer

$$5 mg$$

Question 7

Which of the following best describes the use of technetium-99m in medical imaging?

Accepted Answer

It is used as a tracer because it emits gamma rays and has a short half-life.

Question 8

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

Accepted Answer

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

Question 9

Which SI unit is used to measure the biological effect of radiation on tissue?

Accepted Answer

Sievert (Sv)

Question 10

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

Accepted Answer

A gamma ray is produced and detected by the scanner.

Question 11

Which of the following statements about the atomic mass of an element is correct?

Accepted Answer

It is the weighted average of all naturally occurring isotopes.

Question 12

Which of the following is a correct symbolic notation for an atom with 15 protons and 16 neutrons?

Accepted Answer

$$^{31}_{15}\mathrm{P}$$

Question 13

Which of the following best explains why cells that are rapidly dividing are more susceptible to ionizing radiation?

Accepted Answer

Their genetic material is exposed more often during cell division.

Question 14

If a stable isotope is bombarded with a neutron to produce a radioisotope, on which side of the nuclear equation does the neutron appear?

Accepted Answer

On the reactant side

Question 15

Which of the following is a real-world example of the use of radioisotopes in therapy?

Accepted Answer

Using iodine-131 to treat thyroid cancer

Question 16

A sample of a radioisotope has a half-life of 3 hours. If you start with 80 mg, how much remains after 9 hours?

Accepted Answer

$$10 mg$$

Question 17

Which of the following forms of radiation is NOT a particle?

Accepted Answer

Gamma

Question 18

What is the main reason why radioisotopes used in medical imaging are chosen to have short half-lives?

Accepted Answer

To minimize the patient's exposure to radiation

Question 19

Which of the following best describes the process of radioactive decay?

Accepted Answer

An unstable nucleus emits radiation to become more stable

Question 20

Which of the following is the correct equation for calculating the remaining amount of a radioactive isotope after $$n$$ half-lives?

Accepted Answer

$$	ext{Remaining amount} = 	ext{Initial amount} 	imes \left(\frac{1}{2}ight)^n$$

Atoms and Radioactivity: Structured Study Notes for General, Organic, and Biological Chemistry

Study Guide - Practice Questions