Question 1

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

Accepted Answer

Proton; in the nucleus

Question 2

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it contain?

Accepted Answer

$$35 - 17 = 18$$ neutrons

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 4

Write the symbolic notation for an atom with 5 protons and 6 neutrons.

Accepted Answer

$$^{11}_{5}\mathrm{B}$$

Question 5

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

Accepted Answer

Gamma ($$\gamma) $$rays

Question 6

A patient receives a dose of 5 mrem of X-ray radiation during a dental exam. According to the clinical effects of radiation exposure, what is the expected outcome?

Accepted Answer

No detectable effect

Question 7

Which equation correctly represents the beta decay of carbon-14?

Accepted Answer

$$^{14}_{6}\mathrm{C} \$$rightarrow ^{14}$$_{7}\mathrm{N} $$+ ^{0}$$_{-1}\mathrm{e}$$

Question 8

A sample contains 250 mCi of a radioisotope in 20 mL. If a patient needs a 50 mCi dose, how many mL should be injected?

Accepted Answer

$$4\ \mathrm{mL}$$

Question 9

Radioactive indium-111 has an effective half-life of 2.5 days. If a patient is injected with 3.0 mCi, how much remains after 10 days?

Accepted Answer

$$0.19\ \mathrm{mCi}$$

Question 10

Which of the following is a correct balanced nuclear equation for the alpha decay of polonium-212?

Accepted Answer

$$^{212}_{84}\mathrm{Po} \$$rightarrow ^{208}$$_{82}\mathrm{Pb} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 11

Which of the following statements about isotopes is TRUE?

Accepted Answer

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

Question 12

Which radioisotope is commonly used in PET scans and what type of emission does it undergo?

Accepted Answer

Fluorine-18; positron emission

Question 13

A sample of chromium-51 (half-life = 27 days) is used in a patient at a dose of 40 μCi. How many days will it take for the activity to fall below 5 μCi?

Accepted Answer

$$81\ \mathrm{days}$$

Question 14

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

Accepted Answer

Mass number is the sum of protons and neutrons in a single atom; atomic mass is the weighted average of all isotopes of an element.

Question 15

Which form of radiation is most dangerous if inhaled or ingested, but is stopped by paper or clothing?

Accepted Answer

Alpha ($$\alpha) $$particles

Question 16

A radioisotope decays by emitting a positron. What happens to the atomic number and mass number of the resulting nucleus?

Accepted Answer

Atomic number decreases by 1; mass number remains the same

Question 17

Which of the following is a real-world application of iodine-131 in medicine?

Accepted Answer

Treatment of thyroid cancer

Question 18

If a radioisotope has a half-life of 6 hours, how much of a 100 mg sample remains after 18 hours?

Accepted Answer

$$12.5\ \mathrm{mg}$$

Question 19

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

Accepted Answer

Their genetic material is exposed more often during cell division.

GOB Chemistry Chapter 2 Study Guide: Atoms, Radioactivity, and Medical Applications

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