Question 1

Which subatomic particle determines the identity of an element, and what is its charge?

Accepted Answer

Proton; positive

Question 2

A neutral atom of sodium (Na) has an atomic number of 11 and a mass number of 23. How many neutrons does it contain?

Accepted Answer

$$23 - 11 = 12$$ 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

Why is the atomic mass of carbon listed as 12.01 amu on the periodic table, even though the most common isotope is carbon-12?

Accepted Answer

Because atomic mass is the average of all isotopes weighted by their abundance

Question 5

Which type of nuclear radiation is most damaging to human tissue if ingested, but least able to penetrate external barriers like skin?

Accepted Answer

Alpha particles

Question 6

A radioactive isotope has a half-life of 8 hours. If you start with 80 mg, how much remains after 24 hours?

Accepted Answer

$$80 \div 2^3$ = 10 mg$$

Question 7

Which of the following nuclear equations correctly represents the alpha decay of thorium-225?

Accepted Answer

$$^{225}_{90}\mathrm{Th} \$$rightarrow ^{221}$$_{88}\mathrm{Ra} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 8

Which emission is represented by the symbol $$^{0}_{-1}\mathrm{e}$$ and what is its charge?

Accepted Answer

Beta particle; $$-1$$

Question 9

A patient receives 25 mCi of Technetium-99 (half-life = 6 hours) for cardiac imaging. How much activity remains after 30 hours?

Accepted Answer

$$25 \div 2^5$ = 0.78$$ mCi

Question 10

Which of the following statements about gamma rays is correct?

Accepted Answer

They are high-energy radiation with no mass or charge

Question 11

Which of the following is a real-life application of radioisotopes in medicine?

Accepted Answer

Brachytherapy for cancer treatment

Question 12

What is the mass number of an oxygen atom with 9 neutrons?

Accepted Answer

$$8 + 9 = 17$$

Question 13

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

Accepted Answer

An unstable nucleus emits radiation to become more stable

Question 14

Which of the following is the correct nuclear equation for the beta decay of cesium-137?

Accepted Answer

$$^{137}_{55}\mathrm{Cs} \$$rightarrow ^{137}$$_{56}\mathrm{Ba} $$+ ^{0}$$_{-1}\mathrm{e}$$

Question 15

If the administered amount of radioactive phosphorus-32 is 10.0 g and the half-life is 10 days, how much remains after 35 days?

Accepted Answer

$$10.0 \div 2$$^{3.5}$$ \approx 1.06 g$$

Question 16

Which of the following particles is emitted when a neutron in an unstable nucleus changes into a proton?

Accepted Answer

Beta particle

Question 17

Which of the following is true about the penetration ability of nuclear emissions?

Accepted Answer

Gamma rays penetrate further than alpha and beta particles

Question 18

What is the charge and symbol for a positron?

Accepted Answer

$$+1$$, $$^{0}_{1}\mathrm{e}$$

Question 19

Which of the following best explains why the atomic mass of gallium is 69.72 amu?

Accepted Answer

It is the weighted average of all naturally occurring isotopes of gallium

Atoms and Radioactivity: Structure, Isotopes, and Nuclear Chemistry

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