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

The $$^{14}\text{C}$$/^{12}$$\text{C}$$ ratio in living organisms remains constant.

Question 1

Which of the following statements best describes the difference between chemical and nuclear reactions?

Accepted Answer

Chemical reactions involve changes in the electronic structure, while nuclear reactions involve changes in the nucleus.

Question 2

A nucleus of uranium-238 undergoes alpha decay. Which nuclear equation correctly represents this process?

Accepted Answer

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

Question 3

Which type of radioactive particle is most easily stopped by a sheet of paper?

Accepted Answer

Alpha particle

Question 4

What is the effect of alpha decay on the atomic number and mass number of a nucleus?

Accepted Answer

Atomic number decreases by 2, mass number decreases by 4

Question 5

Which isotope is most likely to undergo beta decay based on its N/Z ratio?

Accepted Answer

An isotope with N/Z = 1.36

Question 6

Which of the following is a property of gamma rays?

Accepted Answer

They are very high-energy electromagnetic radiation

Question 7

Which nuclear process is responsible for the production of energy in the Sun?

Accepted Answer

Nuclear fusion of hydrogen nuclei

Question 8

A radioactive isotope has a half-life of 5 years. If you start with 80 g, how much will remain after 15 years?

Accepted Answer

10 g

Question 9

Which equation describes the first-order kinetics of radioactive decay?

Accepted Answer

$$N_t = N_0$ e$$^{-\lambda t}$$

Question 10

Which of the following statements about radiocarbon dating is correct?

Accepted Answer

The $$^{14}	ext{C}$$/^{12}$$	ext{C}$$ ratio in living organisms remains constant.

Question 11

Which of the following best explains why most stable nuclei have even numbers of protons and neutrons?

Accepted Answer

Even numbers correspond to closed energy levels, increasing stability.

Question 12

What is the binding energy per nucleon for a nucleus with a total binding energy of 110.74 MeV and 16 nucleons?

Accepted Answer

$$6.921\ 	ext{MeV/nucleon}$$

Question 13

Which of the following is NOT a plausible effect of ionizing radiation on biological molecules?

Accepted Answer

Increasing the stability of DNA

Question 14

Which of the following radioactive decay modes results in the atomic number decreasing by one, but the mass number remaining unchanged?

Accepted Answer

Positron emission

Question 15

Which isotope is commonly used in PET scans due to its short half-life and mode of decay?

Accepted Answer

F-18, beta decay

Question 16

Which of the following statements about nuclear fission is correct?

Accepted Answer

Fission produces two large nuclei and releases energy.

Question 17

What is the minimum amount of fissionable material required to sustain a nuclear chain reaction called?

Accepted Answer

Critical mass

Question 18

Which of the following best describes the energy released in nuclear fission?

Accepted Answer

It is due to the conversion of mass into energy, as described by $$E = mc^2$.

Question 19

Which of the following is a reason why nuclear fusion is not yet widely used for energy production on Earth?

Accepted Answer

Fusion requires extremely high temperatures to overcome nuclear repulsion.

Chapter 20: Nuclear Chemistry – Structure, Reactions, and Applications

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