Chapter 11
Which one of the following radioactive isotopes is useful in the investigation of thyroid problems?
Iodine-131
Which process will result in an increase in the binding energy per nucleon?
A) fission of large radioactive nuclei B) fusion of small nuclei C) both A and B
Ionizing radiation
A) is radiation of sufficient energy to produce ions. B) is radiation of sufficient energy to remove electrons from atoms. C) is radiation of sufficient energy to produce charged atoms. D) All of the above describe ionizing radiation.
Radioisotopes have been used as tracers in a variety of applications because
A) radioactive isotopes of an element have the same chemical properties as nonradioactive isotopes. B) it is easy to follow the movement of a radioactive isotope. C) the decay products are easily detected. D) all of the above are true.
Alpha particles can be stopped by a
A) sheet of paper. B) block of wood. C) thin sheet of aluminum. D) all of these
A "dirty bomb" creates a nuclear explosion.
F
A helium nucleus contains two protons and two neutrons. The mass of the helium nucleus is greater than the combined masses of two protons and two neutrons because binding energy has been added.
F
After one half-life, 50% of a radioactive sample will remain. After the second half-life, none of the radioactivity will be left.
F
Alpha particles will penetrate much farther into a sample than beta particles will.
F
Iodine-131 from radioactive fallout will concentrate in the thyroid gland. However, it has only a short half life and therefore poses only minimal health risks to humans.
F
It will take two half-lives for all of a radioactive sample to decay.
F
Nuclear equations must have the same number of protons on each side of the equation.
F
Nuclear power plants require fuel that has a higher percentage of Uranium-235 than needed for a bomb.
F
Radioactive dating can only be used to date very old objects.
F
The percentage of electricity generated by nuclear power is much higher in the United States than in France.
F
Uranium-238 can undergo nuclear fission, but uranium-235 does not.
F
The major reaction in the sun is the fusion of four hydrogen nuclei to produce a helium nucleus and two positrons.
T
Which of the following statements about nuclear power plants is NOT true?
The uranium fuel used contains over 90% of 235U.
Nitrogen-13 has a half-life of 10 minutes. How much of a 16 mg sample would remain after 40 minutes?
1 mg
Naturally occurring uranium contains approximately what percentage of uranium-235, the isotope that undergoes fission?
1%
If it were possible to obtain a cubic centimeter of pure atomic nuclei, its mass would be approximately
1.2 × 1011 kg.
After three half-lives, what fraction of the original radioactive isotope remains in a sample?
1/8
The amount of a radioactive isotope that remains after two half-lives have passed is
25%
Sodium-24 has a half-life of 15 hours. How much of a 20 mg sample would remain after two half-lives?
5 mg
The following nuclear reaction is an example of 226Ra88 = 4He2 + 222Rn86
Alpha decay
With the discovery of nuclear reactions, and particularly transmutation, which of the following postulates of Dalton's atomic theory must be modified?
Atoms may not be changed into other atoms.
Ernest Rutherford bombarded nitrogen-14 with alpha particles and produced oxygen-17 and a proton. What was the significance of this experiment?
It showed that protons were part of the nucleus for an atom other than hydrogen.
Which scientist won a Nobel prize for chemistry in recognition of his work involving the structure of proteins, and the Nobel prize for peace for his efforts in controlling nuclear weapons?
Linus Pauling
Which of the following resulted in the first demonstration of artificial transmutation?
Rutherford's bombardment of nitrogen-14 with alpha particles
Artificial transmutation can occur when nuclei are bombarded with small particles, such as alpha particles, neutrons or other subatomic particles.
T
Nuclear reaction rates are not affected by changes in temperature.
T
Nuclear science has saved many more lives than have been destroyed by nuclear bombs.
T
Over 75% of the radiation to which the average person is exposed comes from natural sources.
T
Plutonium-239 can undergo nuclear fission.
T
Radioactive isotopes and nonradioactive isotopes of an element react essentially identically.
T
Strontium-90 from radioactive fallout poses a significant risk to human health because it is chemically similar to calcium and can be incorporated into bone.
T
Which of the following statements about the use of radioisotopes to irradiate foods is NOT true?
The taste and appearance of irradiated food undergoes a major change.
UF6 containing uranium-235 can be separated from UF6 containing uranium-238 because
UF6 containing uranium-235 is lighter and will travel faster than UF6 containing uranium-238.
The process of electron capture results in what change in the atomic number?
a decrease of 1
The process of positron emission results in what change in the atomic number?
a decrease of 1
The process of alpha decay results in what change in the atomic number?
a decrease of 2
The radioactive decay of 99mTc to 99Tc MUST occur with the emission of
a gamma ray alone.
The most stable elements have
a high binding energy per nucleon.
When potassium-39 is bombarded by neutrons, chlorine-36 is produced. What other particle is emitted?
alpha particle
Which of the following particles has a mass of 4 amu and a charge of 2+?
alpha particle
The process of beta decay results in what change in the atomic number?
an increase of 1
One difference between a chemical reaction and a nuclear reaction is that in a nuclear reaction
atoms often change from one element to another.
The atomic number increases by 1 during what type of radioactive decay?
beta
In 1932, James Chadwick bombarded beryllium-9 with alpha particles. One product was a neutron. This led to the direct experimental verification of the existence of neutrons. The other product of Chadwick's nuclear reaction was
carbon-12.
The isotope of carbon that is used for radioisotopic dating of previously living objects is
carbon-14.
The process of beta emission can be envisioned as the
conversion of a neutron to a proton and electron. The electron is emitted.
The process of positron emission can be considered as the
conversion of a proton to an neutron and a positron. The positron is emitted
The process of electron capture can be considered as the
conversion of an electron and a proton to a neutron.
Positron emission tomography (PET) is a
diagnostic technique for monitoring dynamic processes in the body, such as brain activity.
Although Albert Einstein is considered one of the greatest scientists of all time, his work generally did not involve much of an aspect that is traditionally associated with science. That aspect is
experiments.
Which one of the following is most penetrating?
gamma ray
Which type of radioactive emission is very similar to X-rays?
gamma ray
The use of radioisotopes as tracers in medical and environmental research takes advantage of the fact that isotopes
generally behave identically in chemical and physical processes.
An alpha particle is the same as a
helium-4 nucleus.
Cosmic rays are
high energy radiation produced by the sun.
Radioactive alpha emitters pose the greatest potential health risk when they are
ingested.
The radioisotope used to determine the size, shape and activity of the thyroid gland is
iodine-131.
Radiation with enough energy to knock electrons off atoms or molecules is known as
ionizing radiation.
Carbon-14 dating of ancient objects is particularly effective because C-14
is continuously produced in the upper atmosphere and its ratio to C-12 in living systems and the environment is constant.
Nuclear fission is a process by which the nucleus of an atom is _________
is induced to split into two or more fragments by some external source.
Nuclear fusion
is the process in which two smaller nuclei combine to form a larger nucleus.
Atoms that have the same atomic number but different numbers of neutrons are
isotopes.
The often tedious process by which a naturally occurring mixture of isotopes is separated and concentrated is called
isotopic enrichment.
Strontium-90 from nuclear fallout is a potential major long term human health threat because
it is chemically similar to calcium and it has a relatively long half-life.
Iodine-131 from nuclear fallout is a potential major short term human health threat because
it is concentrated in the thyroid and has a relatively short half-life.
A piece of cloth is dated using carbon-14. The cloth is determined to be 1400 years old. The half-life of C-14 is 5730 years. The C-14 radioactivity in the cloth will be ________ the radioactivity in a new cloth.
less than
Exposure to radioactive material is considered safe after 10 half-lives because
less than a tenth of 1% of the material remains.
Technetium-99m is a radioisotope used in a variety of diagnostic tests. Technetium-99m has a short half-life (6 hr). The advantage of a short half-life for diagnostic purposes is
the radioactivity does not linger in the body.
Radioisotopes have been used to determine the age of all of the following EXCEPT
living plants
In the famous relationship: E = mc2, the symbol m represents
mass
The major part of the average exposure of humans to radiation comes from
naturally occurring sources.
In the fission of uranium-235, which particle causes and propagates the chain reaction?
neutron
Gadolinium-153 is the most widely used radioisotope in medicine. It is used for the detection of
osteoporosis.
The diameter of an atom is 100,000 times as great as the diameter of its nucleus. If an atom could be expanded to the size of a classroom the nucleus would be about the size of a
period at the end of a sentence.
The nuclear synthesis of plutonium-239 was an important part of the effort to build an atomic bomb during World War II because
plutonium-239 is fissionable.
The medical application of cobalt-60 is
radiation cancer therapy.
Gamma rays can be stopped by
several centimeters of lead.
Phosphorus-30 decays by positron emission. The product is
silicon-30.
In nuclear fusion,
smaller, relatively stable, nuclei are forced together to create a larger nucleus with the release of binding energy.
The mass of a helium nucleus is slightly less than the sum of its parts (2 protons and 2 neutrons) because
some of the mass is converted to binding energy.
In carbon-14 dating
the radioactivity of carbon occurs naturally.
Cesium-137 and Strontium-90 are both produced in nuclear fallout. Cesium-137 has a half-life of 30 years. Strontium-90 has a half-life of 28 years. Strontium-90 is considered to be a greater health threat because
strontium is chemically similar to calcium and is incorporated into bone.
Which of the following isotopes produced in fission bomb explosions poses the greatest health risk to humans?
strontium-90
The source of the energy produced by the sun is
the fusion of primarily hydrogen.
The commercial generation of power from a fusion reaction is not yet practical because of
the high temperatures needed.
Critical mass is
the minimum amount of fissionable material that will sustain a chain reaction.
The factor that is NOT a detriment to the building of nuclear power plants is
the possibility of a "nuclear bomb-like" explosion
Which of the following was NOT a goal of the Manhattan project?
to determine the amount of uranium-235 needed for an atomic power plant
The bombardment of nitrogen-14 with alpha particles produces oxygen-17 and a proton. This process is called
transmutation.
In positron emission tomography (PET), a positron collides with an electron and the two particles disappear in a burst of
two gamma rays.