Exposure to radioactive material is considered safe after 10 half-lives because
less than a tenth of 1% of the material remains.
Which of the following particles has a mass of 1 amu and a charge of 0?
neutron
Positron emission tomography (PET) is a
diagnostic technique for monitoring dynamic processes in the body, such as brain activity.
After five half-lives, what percentage of the original radioactive isotope remains in a sample?
3.13%
When thorium-234 undergoes beta decay, what other product is formed?
protactinium-234
Radioactive alpha emitters pose the greatest potential health risk when they are
ingested
Which of the following statements about transmutation is true? In transmutation
the original element changes into a different element
Stagg Field, at the University of Chicago, is where
the first nuclear pile was built
The atomic number increases by 1 during what type of radioactive decay?
beta
Radiation with enough energy to knock electrons off atoms or molecules is known as
ionizing radiation
an alpha particle is the same as
helium-4 nucleus.
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 often tedious process by which a naturally occurring mixture of isotopes is separated and concentrated is called
isotopic enrichment
Nitrogen-13 has a half-life of 10 minutes. How much of a 128 mg sample would remain after 20 minutes?
32mg
Critical mass is
the minimum amount of fissionable material that will sustain a chain reaction.
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
Phosphorus-30 decays by positron emission. The product is
silicon-30
When radium-223 undergoes alpha decay, what other product is formed?
radon-219
The major part of the average exposure of humans to radiation comes from
naturally occurring sources
The process of electron capture results in what change in the atomic number?
a decrease of 1
After one half-life, 50% of a radioactive sample will remain. After the second half-life, none of the radioactivity will be left
false
The source of the energy produced by the sun is
the fusion of primarily hydrogen
Vitrification has been proposed as one method for dealing with the problem of radioactive waste. What is vitrification?
encapsulating radioactive wastes in glass
The isotope of carbon that is used for radioisotopic dating of previously living objects is
carbon-14
Nuclear fission is a process by which the nucleus of an atom
is induced to split into two or more fragments by some external source.
Alpha particles can be stopped by a
A) block of wood.
B) sheet of paper.
C) all of these*
D) thin sheet of aluminum.
The radioisotope used to determine the size, shape and activity of the thyroid gland is
iodine-131
Balanced nuclear equations must have the same number of electrons on each side of the equation
false
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.
One difference between a chemical reaction and a nuclear reaction is that in a nuclear reaction
atoms often change from one element to another.
Artificial transmutation can occur when nuclei are bombarded with small particles, such as alpha particles, neutrons or other subatomic particles
true
The percentage of electricity generated by nuclear power is much higher in the United States than in France
false
Over 75% of the radiation to which the average person is exposed comes from natural sources
true
Nitrogen-13 has a half-life of 10 minutes. How much of a 128 mg sample would remain after 20 minutes?
32mg
The commercial generation of power from a fusion reaction is not yet practical because of
the high temperatures needed
Which of the following statements about the use of radioisotopes to irradiate foods is NOT true?
A) Radioisotopes kill microorganisms that cause food spoilage.
B) Irradiation has been used for years in some countries.
C) The taste and appearance of irradiated food undergoes a major change.*
D) There is no residual radiation left in the food after irradiation.
It will take three half-lives for all of a radioactive sample to decay.
false
When beryllium-9 is bombarded by alpha particles , carbon-12 is produced. What other particle is emitted?
a neutron