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Flashcards in Nuclear chemistry Deck (38)
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1
Q

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

A

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

2
Q

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

A

neutron

3
Q

Positron emission tomography (PET) is a

A

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

4
Q

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

A

3.13%

5
Q

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

A

protactinium-234

6
Q

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

A

ingested

7
Q

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

A

the original element changes into a different element

8
Q

Stagg Field, at the University of Chicago, is where

A

the first nuclear pile was built

9
Q

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

A

beta

10
Q

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

A

ionizing radiation

11
Q

an alpha particle is the same as

A

helium-4 nucleus.

12
Q

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

A

period at the end of a sentence

13
Q

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

A

isotopic enrichment

14
Q

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

A

32mg

15
Q

Critical mass is

A

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

16
Q

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

A

carbon-12

17
Q

Phosphorus-30 decays by positron emission. The product is

A

silicon-30

18
Q

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

A

radon-219

19
Q

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

A

naturally occurring sources

20
Q

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

A

a decrease of 1

21
Q

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

A

false

22
Q

The source of the energy produced by the sun is

A

the fusion of primarily hydrogen

23
Q

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

A

encapsulating radioactive wastes in glass

24
Q

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

A

carbon-14

25
Q

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

A

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

26
Q

Alpha particles can be stopped by a

A

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

27
Q

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

A

iodine-131

28
Q

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

A

false

29
Q

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

A

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

30
Q

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

A

atoms often change from one element to another.

31
Q

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

A

true

32
Q

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

A

false

33
Q

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

A

true

34
Q

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

A

32mg

35
Q

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

A

the high temperatures needed

36
Q

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

A

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.

37
Q

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

A

false

38
Q

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

A

a neutron