Question 1

The graph above shows the decay curve for a certain radioactive substance. The half- life of this substance is approximately

Accepted Answer

A)  0.5 days. 
B)  2 days. 
C)  1.5 days. 
D)  1 day. 
E)  3 days.

Question 2

The forces that hold the nucleus together

Accepted Answer

A)  act over only very short distances. 
B)  are much stronger than electromagnetic forces. 
C)  Both of the above. 
D)  are attractive, that is, they pull in the inward direction. 
E)  All of the above.

Question 3

Of the following list, the one that gives the smallest average ionizing radiation dose per person per year is

Accepted Answer

A)  cosmic rays. 
B)  nuclear power plants in normal operation. 
C)  radon gas. 
D)  medical X- rays. 
E)  the rocks and soil of Earth.

Question 4

Suppose that a certain saber- toothed- tiger contained one gram of 14C [half- life 6000 years] when it died. The approximate 14C content of the remains of this tiger 24,000 years later would be

Accepted Answer

A)  zero grams. 
B)  1/32 gram. 
C)  1/16 gram. 
D)  1/8 gram. 
E)  impossible to predict.

Question 5

Consider the three following forces: gravitational, electromagnetic, and strong nuclear. Of these three, which one or ones have significant effects [i.e., experimentally detectable effects] within the nucleus?

Accepted Answer

A)  electromagnetic and strong nuclear only 
B)  all three 
C)  electromagnetic only 
D)  gravitational and strong nuclear only 
E)  strong nuclear only

Question 6

234 Th beta- decays. The resulting nucleus has atomic number

Accepted Answer

A)  230. 
B)  90. 
C)  234. 
D)  91. 
E)  88.

Question 7

Can an element decay "backward" in the periodic table, to a lower atomic number?

Accepted Answer

A)  No, in fact elements cannot alter their atomic number by radioactive decay. 
B)  No, but an element can decay to a higher atomic number. 
C)  Yes, by alpha decay. 
D)  Yes, by beta decay. 
E)  Yes, radioactive decay always causes elements to decay to a lower atomic number.

Question 8

The biological damage caused by radioactive materials is due to

Accepted Answer

A)  nuclear fusion occurring within biological cells. 
B)  thermal energy created by radioactive decay within biological cells. 
C)  nuclear fission occurring within biological cells. 
D)  the fast- moving alpha, beta, and gamma particles passing through biological cells. 
E)  the fast- moving daughter nuclei [or residual nuclei] passing through biological cells.

Question 9

90 Sr is a radioactive isotope that decays by beta- decay. Its daughter nucleus is

Accepted Answer

A)  "86 Kr." 
B)  "89 Y." 
C)  "90 Y." 
D)  "89 Rb." 
E)  "88 Rb."

Question 10

Where does most of Earth's 14C come from?

Accepted Answer

A)  It is continually being formed as a result of the photosynthesis process 
B)  It is continually being formed by the impact of cosmic rays on the atmosphere. 
C)  It comes to Earth from outer space along with other cosmic rays. 
D)  It was deposited on Earth when the solar system first evolved. 
E)  It was deposited on Earth many years ago by meteors.

Question 11

According to our best present predictions about the medical consequences of the Chernobyl nuclear power plant accident, the longer- term cancer deaths caused by that accident will

Accepted Answer

A)  be medically indistinguishable from cancer deaths produced by other causes. 
B)  be very difficult, or impossible, to detect statistically among the large number of other cancer deaths. 
C)  be much more numerous than the roughly 40 deaths caused directly by short- term radiation effects. 
D)  All of the above. 
E)  None of the above.

Question 12

The isotope 238 U alpha decays to the daughter nucleus

Accepted Answer

A)  "234 U." 
B)  "238 Np." 
C)  "234 Th." 
D)  "234 u." 
E)  "236 Th.
92 93"

Question 13

How do 3 H and 3 He differ? 1 2

Accepted Answer

A)  in their number of protons 
B)  in their number of neutrons 
C)  in both of the above ways 
D)  in their chemical behavior 
E)  in all of the above ways

Question 14

Radioactive decay occurs when

Accepted Answer

A)  bacteria and other microscopic organisms digest nuclear particles. 
B)  a nucleus is struck and broken into pieces by a fast moving particle. 
C)  an atom loses one or more orbital electrons. 
D)  a nucleus emits a particle spontaneously 
E)  two or more nuclei fuse together.

Question 15

Radon is

Accepted Answer

A)  the radioactive substance that will probably be used to irradiate and sterilize food. 
B)  the main component in the radioactive fallout from nuclear weapons and nuclear power plant accidents. 
C)  a type of electromagnetic radiation that is produced by the sun and partially penetrates Earth's atmosphere. 
D)  a radioactive gas produced by the rocks and soil that can filter into houses. 
E)  the chemically active element in asbestos.

Question 16

Quantum uncertainties are the source of

Accepted Answer

A)  the unpredictability of radioactive decay. 
B)  the unpredictability of games of chance such as flipping coins. 
C)  Both of the above. 
D)  None of the above.

Question 17

The fundamental force responsible for the chemical properties of atoms is

Accepted Answer

A)  the strong nuclear force. 
B)  gravity. 
C)  friction. 
D)  the weak nuclear force. 
E)  the electromagnetic force.

Question 18

Two different isotopes of the same element have

Accepted Answer

A)  different chemical properties. 
B)  different numbers of protons but the same number of neutrons. 
C)  different numbers of electrons. 
D)  the same number of protons, but different numbers of neutrons. 
E)  different numbers of both protons and neutrons.

Question 19

The isotope 3 H has

Accepted Answer

A)  1 neutron and 2 protons. 
B)  1 proton and 2 neutrons. 
C)  1 neutron and 3 protons. 
D)  1 proton and 3 neutrons. 
E)  None of the above.

Question 20

Radioactive isotopes are useful for

Accepted Answer

A)  tracing the path of certain chemicals. 
B)  cancer therapy. 
C)  dating the ages of objects. 
D)  All of the above. 
E)  None of the above.

Exam 14: The Nucleus and Radioactivity: an New Force

The graph above shows the decay curve for a certain radioactive substance. The half- life of this substance is approximately

The forces that hold the nucleus together

Of the following list, the one that gives the smallest average ionizing radiation dose per person per year is

Suppose that a certain saber- toothed- tiger contained one gram of ¹⁴C [half- life 6000 years] when it died. The approximate ¹⁴C content of the remains of this tiger 24,000 years later would be

Consider the three following forces: gravitational, electromagnetic, and strong nuclear. Of these three, which one or ones have significant effects [i.e., experimentally detectable effects] within the nucleus?

²³⁴Th beta- decays. The resulting nucleus has atomic number

Can an element decay "backward" in the periodic table, to a lower atomic number?

The biological damage caused by radioactive materials is due to

⁹⁰Sr is a radioactive isotope that decays by beta- decay. Its daughter nucleus is

Where does most of Earth's ¹⁴C come from?