Question 1

Which of the following statements best explains why $$^{24}_{12}\mathrm{Mg}$$, $$^{25}_{12}\mathrm{Mg}$$, and $$^{26}_{12}\mathrm{Mg}$$ are considered isotopes of magnesium?

Accepted Answer

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

Question 2

Which isotope listed below is stable according to the provided data?

Accepted Answer

$$^{24}_{12}\mathrm{Mg}$$

Question 3

What is the nuclear equation for the alpha decay of $$^{238}_{92}\mathrm{U}$$?

Accepted Answer

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

Question 4

Which type of radiation has the greatest penetrating ability and requires thick lead or concrete to be effectively blocked?

Accepted Answer

Gamma rays

Question 5

A radioactive isotope has a half-life of 8 days. If you start with 40 mg, how much remains after 24 days?

Accepted Answer

5 mg

Question 6

Which of the following best describes what happens during beta decay?

Accepted Answer

A neutron is converted into a proton and an electron, and the electron is emitted.

Question 7

Which of the following is the correct symbol for a positron?

Accepted Answer

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

Question 8

A patient receives a dose of 0.7 mSv from a lumbar spine X-ray. How does this compare to the average annual background radiation dose received by an American?

Accepted Answer

It is about one-fifth of the average annual dose (3.6 mSv).

Question 9

Which of the following best explains why $$^{131}_{53}\mathrm{I} is $$used to treat thyroid disorders?

Accepted Answer

It is absorbed by the thyroid and emits beta particles that destroy overactive thyroid tissue.

Question 10

Which of the following nuclear reactions represents positron emission?

Accepted Answer

$$^{49}_{24}\mathrm{Cr} \$$rightarrow ^{49}$$_{25}\mathrm{Mn} $$+ ^{0}$$_{1}\mathrm{e}$$

Question 11

Which of the following statements about the biological effects of radiation is correct?

Accepted Answer

A dose of 5 Sv is lethal to about 50% of humans.

Question 12

Which of the following best describes a chain reaction in nuclear fission?

Accepted Answer

Neutrons released from one fission event cause additional fission events in other nuclei.

Question 13

Which of the following is a correct description of gamma emission?

Accepted Answer

The nucleus releases energy as a photon without changing its atomic number or mass number.

Question 14

A sample of $$^{131}_{53}\mathrm{I}$$ has a half-life of 8 days. If a patient is given 16 mg, how much will remain after 32 days?

Accepted Answer

1 mg

Question 15

Which of the following is a real-world application of positron emission tomography (PET) scans?

Accepted Answer

Imaging metabolic activity in the brain using a positron-emitting isotope.

Question 16

Which of the following best explains why $$^{238}_{92}\mathrm{U} is $$used as a fuel in nuclear reactors?

Accepted Answer

It undergoes fission, releasing large amounts of energy and neutrons that sustain a chain reaction.

Question 17

Which of the following is the correct relationship between the units of absorbed dose and biological damage?

Accepted Answer

$$1\ \mathrm{Sv} = 100\ \mathrm{rem}$$

Question 18

Which of the following best describes the process of carbon dating?

Accepted Answer

Measuring the ratio of $$^{14}\mathrm{C} to$$ $$^{12}\mathrm{C} in a $$sample to estimate its age.

Chapter 5: Nuclear Chemistry and Radioactivity Study Guide

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