Question 1

Which of the following statements best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 2

Which nuclear 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 3

What is emitted during the beta decay of tritium ($$^3_1\mathrm{H}$$)?

Accepted Answer

An electron

Question 4

Which type of radioactive decay results in the emission of a particle with a $$+1$$ charge and no significant mass?

Accepted Answer

Positron emission

Question 5

What is the balanced nuclear equation for the beta decay of chromium-51 ($$^{51}_{24}\mathrm{Cr}$$)?

Accepted Answer

$$^{51}_{24}\mathrm{Cr} \$$rightarrow ^{51}$$_{25}\mathrm{Mn} $$+ ^{0}$$_{-1}\mathrm{e}$$

Question 6

Which of the following processes does NOT change the atomic number of the nucleus?

Accepted Answer

Gamma emission

Question 7

A radioactive isotope undergoes electron capture. What happens to its atomic number and mass number?

Accepted Answer

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

Question 8

Which type of radioactive decay is most likely for a nucleus with a high neutron-to-proton ratio?

Accepted Answer

Beta emission

Question 9

Which of the following is true about gamma radiation?

Accepted Answer

It is a high-energy photon with no mass or charge.

Question 10

What is the effect of alpha decay on the neutron-to-proton ratio of a nucleus?

Accepted Answer

It increases the neutron-to-proton ratio.

Question 11

Which of the following nuclear equations represents positron emission?

Accepted Answer

$$^{7}_{4}\mathrm{Be} \$$rightarrow ^{7}$$_{3}\mathrm{Li} $$+ ^{0}$$_{+1}\mathrm{e}$$

Question 12

Which of the following best explains why gamma emission is useful in medical diagnostics?

Accepted Answer

Gamma rays are pure energy and can pass through the body to detection equipment.

Question 13

Which of the following is a correct statement about the law of conservation of mass in nuclear reactions?

Accepted Answer

The sum of atomic numbers and mass numbers must be equal on both sides of the equation.

Question 14

A nucleus with a lower neutron-to-proton ratio is most likely to undergo which type of decay?

Accepted Answer

Alpha emission or positron emission

Question 15

Which of the following is the correct balanced nuclear equation for the alpha decay of polonium-241?

Accepted Answer

$$^{241}_{84}\mathrm{Po} \$$rightarrow ^{237}$$_{82}\mathrm{Pb} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 16

Which of the following best describes what happens during electron capture?

Accepted Answer

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

Question 17

Which of the following isotopes is most likely to be radioactive?

Accepted Answer

$$^{238}_{92}\mathrm{U}$$

Question 18

Which of the following is a property of alpha particles?

Accepted Answer

They are identical to helium nuclei.

Question 19

Which of the following processes increases the neutron-to-proton ratio in a nucleus?

Accepted Answer

Alpha emission

Question 20

A sample of technetium-99m ($$^{99m}_{43}\mathrm{Tc}) is $$used in a medical scan. What type of radiation is primarily emitted?

Accepted Answer

Gamma rays

Chapter 20: Nuclear Chemistry – Radioactive Isotopes and Nuclear Reactions

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