Chapter 21 Test Review

Question 1

The half-life of cobalt-70 is 5.3 years. How much of a 1.000 mg sample of cobalt-60 is left after 15.9 years?

Answer 1

A1=1.000x0.5^15.9/5.3
A1=0.125 mg

Question 2

Tritium a radioactive isotope of hydrogen has a half-life of 12.3 years. If you begin with 1.5mg of this isotope, how many mg remain after 49.2 years?

Answer 2

A1=1.5x0.5^49.2/12.3
A1=.09 mg

Question 3

Gallium citrate containing the radioactive isotope gallium-67 is used medically as a tumor seeming agent. It has a half life of 77.9 hrs. How much time is needed for a sample of gallium citrate to decay to 10% of its original activity?

Answer 3

1/10=0.5^T/77.9
Log (1/10/.5)= T/77.9
T=259 hrs

Question 4

Technetium-99 a gamma ray emitter is used in medical imaging. A sample of this isotope emits 3.28x10^5 photon/s. After 1.0 hrs the gamma ray emitter has dropped to 2.9x10^5 photons/s. Calculate the half life of technetium-99?

Answer 4

Log(2.9x10^5/3.28x10^5)/Log0.5=1.0/t
t1/2= 5.6 hours

Question 5

Radium decaying by alpha emission

Answer 5

Radon+4He2= 226 Ra

Question 6

Carbon-14 decay by beta emission

Answer 6

14carbon6= 0e-1+14N

Question 7

Xe decays by positron emission

Answer 7

118xe=0e1+177I53

Question 8

Magic Numbers

Answer 8

Protons: 2,8,20,28,52,82
Neutrons: 2,8,28,50, 82, 126

Question 9

Most elements found using fission are…

Answer 9

Radioactive

Question 10

Fusion products are generally…

Answer 10

NOT radioactive

Question 11

Alpha particle

Answer 11

4He2

Question 12

Beta Particle

Answer 12

0e-1 (neutron rich)

Question 13

Position particle

Answer 13

0e1 same as electron opposite charge
Neutron poor

Question 14

Electron capture

Answer 14

0e-1 neutron poor

Question 15

What causes fission?

Answer 15

A SLOW moving nêutron striking a nucleus

Question 16

What are the 3 stable isotopes of Uranium?

Answer 16

Uranium-234
Uranium-235
Uranium-238
All have the same number of protons but different number of neutrons

Question 17

Which Nuclei are especially stable? Why? 4He2, 40Ca20, 98Tc43

Answer 17

He and Ca are the especially stable nuclei because they contain TWO even numbers

Question 18

As the number of protons increases…

Answer 18

The repulsive force also increases

Question 19

All atoms with an atomic number greater than 83 are…

Answer 19

Radioactive

Question 20

Unstable nuclei are caused by…

Answer 20

Having too many or too few neutrons

Question 21

A nucleus becomes stable by …

Answer 21

Emitting radiation through nuclear reactions

Question 22

A nuclear reaction…

Answer 22

Changes the identity of a nucleus

Question 23

During transmutation

Answer 23

Charge and mass will be conserved

Question 24

Alpha penetration

Answer 24

Ability is low, stopped by paper, and dangerous if ingested

Question 25

Beta penetration

Answer 25

Ability is medium and is stopped by clothing

Question 26

Gamma penetration

Answer 26

Ability is high; and is the mos dangerous to the body

Question 27

Transmutation types include…

Answer 27

Natural decay, k-emission, fission, and fusion

Question 28

If there is only ONE reactant

Answer 28

Alpha, Beta, or position emission

Question 29

Decay series…

Answer 29

Is a series of decay steps a parent nuclide takes to become a stable daughter nuclide

Question 30

Nuclear fission

Answer 30

Nucleus splits into 2+ fragments and release energy

Question 31

Controlled chain

Answer 31

Can be harnessed as nuclear energy

Question 32

Moderator

Answer 32

Material that slows down neutrons and speeds up fission (water, and graphite)

Question 33

Fuel rods

Answer 33

Contains the radioactive material that fissions and super heats the water

Question 34

Control rods

Answer 34

Absorb excess neutrons and keeps them from passing through (boron and cadmium)

Question 35

Containment vessels

Answer 35

Sheiks the radiation from escaping into the environment

Question 36

Cooling tower

Answer 36

Allows excess heat from the heated water to cool down

Question 37

Spent fuel rods

Answer 37

Kept on site in pools until stored in dry casks

Question 38

Nuclear Power PROS:

Answer 38

- more power - non-air polluting - efficient energy

Question 39

Nuclear power CONS:

Answer 39

- radioactive waste - radioactive disposal - meltdown - 60-70 year operational period

Question 40

When uranium decays into lead, lead is considered…

Answer 40

The daughter nuclei

Question 41

In order to use radiometric dating, scientists need to…

Answer 41

Measure the rate that radioactive elements decay

Question 42

For scientists to dat rocks, scientists…

Answer 42

Measure the ratio of U to Pb

Question 43

When uranium decays into lead, uranium is considered…

Answer 43

The parent atom

Question 44

Scientists date the age of the earth by…

Answer 44

Radiometric dating using radioisotopes found in rocks

Question 45

The rate of a parent atom decaying into a daughter atom is a …

Answer 45

Constant

Question 46

When 50% of the parent atoms become daughters this is called…

Answer 46

Half-Life

Question 47

What subatomic particle is necessary to start and keep a fission Chain reaction going

Answer 47

Neutron

Question 48

Nuclear Fusion

Answer 48

The process in which LIGHT nuclei combine at extremely high temperatures, forming heavier nuclei, and releasing energy

Question 49

Stars are powered by….

Answer 49

Nuclear fusion

Question 50

Deuterium and tritium are isotopes of ….

Answer 50

Hydrogen

Question 51

Fusion ADVANTAGES:

Answer 51

-great weapon -abundance of fuel -can make new elements

Question 52

Fusion DISADVANTAGES:

Answer 52

- not able to produce enough energy to sustain the reaction

Question 53

Background radiation

Answer 53

The radiation that arises naturally from cosmic rays and from radioisotopes in soil, rocks, food, and air

Question 54

Harmful radiation

Answer 54

Prolonged Genetically mutate or destroy cells Can cause radiation sickness, hair loss, and cancers High doses: can cause death within a couple days or weeks

Question 55

To protect yourself from radiation…

Answer 55

Limit exposure, clothing, distance, and time of exposure

Question 56

Radioactive decay application

Answer 56

Tells us how old rocks and artifacts are; carbon-14 is good for dating specimens

Question 57

Uses in medicine

Answer 57

Tracers to diagnose a disease Can be used to treat cancer PET scans for brains

Question 58

Uses in food and technology

Answer 58

Irrigation roots Sanitize good Space exploration and powering of submarine

Question 59

Water reactor. How does it work?

Answer 59

A nuclear reacted heats water and prices steam inside the reactor vessel. Water is then pumped through the reactor core and heated by fission. Pipes then feed the steam directly into the turbine to produce electricity

Question 60

The Band Of Stability

Answer 60

The band of stability represent the area where stable, non-radioactive isotopes exist based on their ratio of neutrons to protons

Question 61

Geiger muller

Answer 61

The GN counter can detect all kinds of radiation such as alpha, gamma, and beta rays

Question 62

Scintillation counter

Answer 62

Detects only ionizing radiations

Question 63

Different types of reactors

Answer 63

- pressurized water reactor - boiling water reactor - advanced gas-cooled reactor - light water graphite moderated reactor -fast neutron reactor -operable nuclear power plants

Question 64

Free radical molecule

Answer 64

An atom or like how containing one or more unpaired electrons