Nuclear chemistry

Question 1

Exposure to radioactive material is considered safe after 10 half-lives because

Answer 1

less than a tenth of 1% of the material remains.

Question 2

Which of the following particles has a mass of 1 amu and a charge of 0?

Answer 2

neutron

Question 3

Positron emission tomography (PET) is a

Answer 3

diagnostic technique for monitoring dynamic processes in the body, such as brain activity.

Question 4

After five half-lives, what percentage of the original radioactive isotope remains in a sample?

Answer 4

3.13%

Question 5

When thorium-234 undergoes beta decay, what other product is formed?

Answer 5

protactinium-234

Question 6

Radioactive alpha emitters pose the greatest potential health risk when they are

Answer 6

ingested

Question 7

Which of the following statements about transmutation is true? In transmutation

Answer 7

the original element changes into a different element

Question 8

Stagg Field, at the University of Chicago, is where

Answer 8

the first nuclear pile was built

Question 9

The atomic number increases by 1 during what type of radioactive decay?

Answer 9

beta

Question 10

Radiation with enough energy to knock electrons off atoms or molecules is known as

Answer 10

ionizing radiation

Question 11

an alpha particle is the same as

Answer 11

helium-4 nucleus.

Question 12

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

Answer 12

period at the end of a sentence

Question 13

The often tedious process by which a naturally occurring mixture of isotopes is separated and concentrated is called

Answer 13

isotopic enrichment

Question 14

Nitrogen-13 has a half-life of 10 minutes. How much of a 128 mg sample would remain after 20 minutes?

Answer 14

32mg

Question 15

Critical mass is

Answer 15

the minimum amount of fissionable material that will sustain a chain reaction.

Question 16

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

Answer 16

carbon-12

Question 17

Phosphorus-30 decays by positron emission. The product is

Answer 17

silicon-30

Question 18

When radium-223 undergoes alpha decay, what other product is formed?

Answer 18

radon-219

Question 19

The major part of the average exposure of humans to radiation comes from

Answer 19

naturally occurring sources

Question 20

The process of electron capture results in what change in the atomic number?

Answer 20

a decrease of 1

Question 21

After one half-life, 50% of a radioactive sample will remain. After the second half-life, none of the radioactivity will be left

Answer 21

false

Question 22

The source of the energy produced by the sun is

Answer 22

the fusion of primarily hydrogen

Question 23

Vitrification has been proposed as one method for dealing with the problem of radioactive waste. What is vitrification?

Answer 23

encapsulating radioactive wastes in glass

Question 24

The isotope of carbon that is used for radioisotopic dating of previously living objects is

Answer 24

carbon-14

Question 25

Nuclear fission is a process by which the nucleus of an atom

Answer 25

is induced to split into two or more fragments by some external source.

Question 26

Alpha particles can be stopped by a

Answer 26

A) block of wood.
B) sheet of paper.
C) all of these*
D) thin sheet of aluminum.

Question 27

The radioisotope used to determine the size, shape and activity of the thyroid gland is

Answer 27

iodine-131

Question 28

Balanced nuclear equations must have the same number of electrons on each side of the equation

Answer 28

false

Question 29

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

Answer 29

strontium is chemically similar to calcium and is incorporated into bone.

Question 30

One difference between a chemical reaction and a nuclear reaction is that in a nuclear reaction

Answer 30

atoms often change from one element to another.

Question 31

Artificial transmutation can occur when nuclei are bombarded with small particles, such as alpha particles, neutrons or other subatomic particles

Answer 31

true

Question 32

The percentage of electricity generated by nuclear power is much higher in the United States than in France

Answer 32

false

Question 33

Over 75% of the radiation to which the average person is exposed comes from natural sources

Answer 33

true

Question 34

Nitrogen-13 has a half-life of 10 minutes. How much of a 128 mg sample would remain after 20 minutes?

Answer 34

32mg

Question 35

The commercial generation of power from a fusion reaction is not yet practical because of

Answer 35

the high temperatures needed

Question 36

Which of the following statements about the use of radioisotopes to irradiate foods is NOT true?

Answer 36

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.

Question 37

It will take three half-lives for all of a radioactive sample to decay.

Answer 37

false

Question 38

When beryllium-9 is bombarded by alpha particles , carbon-12 is produced. What other particle is emitted?

Answer 38

a neutron