Deck 16: The Atomic Nucleus and Radioactivity

Question 1

Compared to the mass of a uranium nucleus before splitting, the pieces it splits into have

A) more mass.
B) the same mass.
C) less mass.

Answer 1

less mass.

Question 2

Fissioning an iron nucleus yields a net

A) release of energy.
B) absorption of energy.
C) neither absorption nor release of energy

Answer 2

absorption of energy.

Question 3

Radioactivity in the world is something

A) relatively new.
B) as old as the world itself.

Answer 3

as old as the world itself.

Question 4

The origin of cosmic rays is the

A) clouds.
B) cosmos.
C) sun.
D) Earth.
E) none of these

Question 5

All deposits of natural uranium contain appreciable amounts of

A) lead.
B) iron.
C) gold.
D) all of these
E) none of these particularly

Question 6

The half-life of an isotope is one day. At the end of two days the amount that remains is

A) none.
B) one-half.
C) one-eighth.
D) one-quarter.
E) none of these

Question 7

A nucleon has more potential energy with respect to a nucleus when it is

A) inside the nucleus.
B) outside the nucleus.
C) both the same

Question 8

When U-239 emits a beta particle, the nucleus left behind has

A) 91 protons.
B) 92 protons.
C) 90 protons.
D) 93 protons.
E) 94 protons.

Question 9

Electric forces within an atomic nucleus tend to

A) hold it together.
B) push it apart.
C) neither of these

Question 10

When a nucleus emits a positron, its atomic number

A) decreases by 1.
B) increases by 1.
C) doesn't change.

Question 11

Fusing two helium nuclei yields a net

A) release of energy.
B) absorption of energy.
C) neither absorption nor release of energy

Question 12

Fissioning a lead nucleus yields a net

A) absorption of energy.
B) release of energy.
C) neither absorption nor release of energy

Question 13

When uranium-238 absorbs a neutron, it

A) fissions.
B) becomes an alpha emitter.
C) emits a neutrino.
D) becomes a beta emitter.
E) all of these

Question 14

Energy released by the sun results from the process wherein atomic nuclei

A) break apart.
B) combine.
C) both of these
D) none of these

Question 15

A nuclear process that has relatively few radioactive by-products is

A) fission.
B) fusion.
C) Both of these have comparable radioactive by-products.

Question 16

A nucleon has the least mass in the nucleus of

A) hydrogen.
B) plutonium.
C) uranium.
D) lead.
E) iron.

Question 17

In nuclear fission and nuclear fusion reactions, the amount of mass converted to energy of other forms is

A) less than 1%.
B) about 30%.
C) about 10%.
D) about 20%.
E) more than 30%.

Question 18

A nucleon has more mass when it is

A) outside the nucleus.
B) inside the nucleus.
C) both the same

Question 19

Detonation of a fusion type hydrogen bomb is started by

A) turning on a laser cross fire.
B) splitting a small piece of uranium.
C) pressing together several small pieces of uranium.
D) igniting a small fission bomb.
E) none of these

Question 20

The fusion torch is a version of

A) a mass spectrometer.
B) a cyclotron.
C) an electron microscope.
D) a hydrogen magnet.
E) a linear accelerator.

Question 21

If carbon were used as nuclear fuel, it would be best

A) fissioned.
B) fused.
C) either fused or fissioned.

Question 22

The energy release in both fission and fusion is mainly in the form of

A) beta radiation.
B) alpha radiation.
C) gamma radiation.
D) kinetic energy of fragments.
E) a combination of alpha, beta, and gamma radiation.

Question 23

It's impossible for a hydrogen atom to emit an alpha particle.

Question 24

A certain radioactive isotope placed near a Geiger counter registers 160 counts per second. Eight hours later, the counter registers 10 counts per second. What is the half life of the isotope?

A) 4 hours
B) 6 hours
C) 8 hours
D) 2 hours
E) none of these

Question 25

When U-238 emits an alpha particle, the nucleus left behind has

A) 94 protons.
B) 90 protons.
C) 93 protons.
D) 91 protons.
E) 92 protons.

Question 26

In gaseous form, at the same temperature, the average speed of U-238 compared to the speed of U-235 is

A) less.
B) more.
C) the same.

Question 27

Detonation of a fission type atomic bomb is started by

A) igniting a small thermonuclear bomb.
B) splitting a small piece of uranium.
C) pressing together several small pieces of uranium.
D) turning on a laser cross fire.
E) none of these

Question 28

Compared to the energy produced by fissioning a single uranium atom, the energy produced by fusing two deuterium atoms is

A) more.
B) less.
C) the same.

Question 29

The source of the Earth's natural heat is

A) molten-hot lava.
B) solar energy in the form of fossil fuels.
C) radioactive decay in the Earth's core.
D) pressure on the Earth's core.

Question 30

When an alpha particle is ejected from a nucleus, the nucleus then has less

A) charge.
B) mass.
C) both of these
D) neither of these

Question 31

Pure elements can be transformed into entirely different elements. This statement at the present
time is

Question 32

An element emits 1 alpha particle, 1 positron, and 3 beta particles. Its atomic number

A) increases by 1.
B) decreases by 2.
C) stays the same.
D) increases by 2.
E) decreases by 1.

Question 33

The most harmful radiations are those that

A) damage living cells.
B) kill living cells.

Question 34

If iron were used as nuclear fuel, it would be best

A) fused.
B) fissioned.
C) neither fused nor fissioned.

Question 35

The function of graphite in the first atomic reactor was to

A) emit fast neutrons.
B) slow fast neutrons.
C) moderate uranium isotopes.
D) absorb fast neutrons.
E) none of these

Question 36

The half life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about

A) 11,500 years.
B) 46,000 years.
C) 716 years.
D) 17,200 years.
E) 22,900 years.

Question 37

X-rays may be regarded as

A) high frequency radio waves.
B) high frequency sound waves.
C) both of these
D) none of these

Question 38

Fissioning helium would yield a net

A) absorption of energy.
B) release of energy.
C) neither absorption nor release of energy

Question 39

In which of these processes is an element of matter changed into a completely different element?

A) nuclear fission
B) nuclear fusion
C) both of these
D) neither of these

Question 40

If an alpha particle and a beta particle have the same energy, which particle will penetrate farther into an object?

A) alpha particle
B) beta particle
C) They both penetrate the same distance.

Question 41

Carbon 14 is produced in the atmosphere principally by

A) photosynthesis.
B) cosmic-ray bombardment.
C) plants and animals.
D) nitrogen bombardment.
E) none of these

Question 42

When uranium emits a beta particle, the result is a

A) protactinium.
B) a transuranic element.
C) a different isotope of uranium.
D) thorium.
E) depends on the isotope of uranium that emits the beta particle

Question 43

The high temperature of the Earth's interior is due mostly to

A) the Earth's natural heat.
B) friction as plates move past one another.
C) radioactivity.
D) great internal pressure.

Question 44

When a beta particle is ejected from a nucleus, the nucleus then has slightly

A) smaller charge and significantly greater mass.
B) greater mass and charge.
C) greater mass and smaller charge.
D) smaller mass and significantly greater charge.

Question 45

Carbon dating requires that the object being tested contain

A) charcoal.
B) sugar molecules.
C) organic material.
D) inorganic material.
E) none of these

Question 46

Generally speaking, the larger a nucleus is, the greater its

A) stability.
B) instability.
C) neither stability nor instability.

Question 47

A sphere of pure U-235 will explode if it is

A) big enough.
B) small enough.
C) shaken hard enough.
D) hot enough.

Question 48

Which will leak more neutrons, two separate lumps of uranium or the same two lumps stuck together?

A) two separate lumps
B) the same two lumps stuck together
C) both the same

Question 49

When thorium (A = 90) emits a beta particle, the resulting nucleus has atomic number

A) 88.
B) 92.
C) 90.
D) 89.
E) none of these

Question 50

Once an alpha particle is outside the nucleus it is

A) quickly bound to a neighboring nucleus.
B) electrostatically repelled.
C) radioactive.
D) free to wander about the nucleus.

Question 51

A chain reaction grows when the average number of liberated neutrons which go on to cause further fissions is

A) less than one.
B) greater than one.
C) zero.
D) one.

Question 52

When an element undergoes nuclear transmutation, the result is a completely different

A) element.
B) ion of the same element.
C) isotope of the same element.

Question 53

Which shape uses the smallest amount of material when creating a critical mass?

A) cone
B) cube
C) sphere
D) elongated box
E) none of these

Question 54

Plutonium is not found in any appreciable amounts in natural ore deposits because it

A) is artificially created.
B) has a short half life.
C) is a gas at room temperature.
D) is chemically inert.
E) none of these

Question 55

Fusing two iron nuclei yields a net

A) release of energy.
B) absorption of energy.
C) neither absorption nor release of energy

Question 56

If all the uranium in the world were exhausted, breeder reactors would be

A) relics of a brief age.
B) used much more than they are now.
C) researched more than they are now.
D) considered more seriously than they are now.
E) none of these

Question 57

If uranium were split into three equal segments instead of two, the reaction would be

A) less energetic.
B) as energetic.
C) more energetic.
D) Not enough information is given for a reasonable estimate.

Question 58

A Geiger counter placed 1 meter from a point source of radiation registers 100 counts per second. If the Geiger counter is moved closer - to 0.5 meter from the source, what will the count rate be?

A) 200 counts/s
B) 100 counts/s
C) 400 counts/s
D) 25 counts/s
E) 50 counts/s

Question 59

The mass of an atomic nucleon is nearly

A) twice the mass of an electron.
B) four times the mass of an electron.
C) a thousand times the mass of an electron.
D) two thousand times the mass of an electron.

Question 60

In a mass spectrometer, a variety of singly-ionized atomic nuclei are directed into a magnetic field where they are deflected and strike a detecting screen. The particles to undergo the greatest
Deflection are the particles with the

A) least mass.
B) greatest mass.
C) same for all

Question 61

When a lump of uranium is broken into smaller pieces, the total surface area of the lump

A) increases.
B) remains the same.
C) decreases.

Question 62

Compared to the sum of the masses of all the individual nucleons in their separate states that make up a nucleus, the mass of the composite nucleus is

A) less.
B) more.
C) the same.

Question 63

The fate of the world's uranium supply is to eventually become

A) alpha and beta particles.
B) lead.
C) iron.

Question 64

The difference in the mass of a nucleon when outside an atomic nucleus compared to inside the nucleus depends on

A) radioactive decay.
B) isotopic abundance.
C) the distance away from the nucleus.
D) the atomic number of the nucleus.
E) gamma emission.

Question 65

An element will decay to an element with higher atomic number in the periodic table if it emits

A) a proton.
B) a beta particle.
C) an alpha particle.
D) a gamma ray.
E) none of these

Question 66

When a beta particle is ejected from a nucleus, the nucleus then has a greater

A) charge.
B) mass.
C) both of these
D) neither of these

Question 67

Electrical forces inside a nucleus contribute nuclear

A) stability.
B) instability.
C) both of these
D) none of these

Question 68

An atom with an imbalance of electrons to protons is

A) an isotope.
B) a hadron.
C) a baryon.
D) an ion.
E) none of these

Question 69

Compared to protons, the reason neutrons are effective nuclear bullets in nuclear reactions is that a neutron has

A) more penetrating power than a proton.
B) more mass than a proton.
C) a wider cross section than a proton.
D) all of these
E) none of these

Question 70

The nucleus with the greatest mass is

A) iron.
B) hydrogen.
C) plutonium.
D) lead.
E) uranium.

Question 71

When the hydrogen isotope tritium-3 emits a beta particle, it becomes an isotope of

A) lithium.
B) hydrogen.
C) carbon.
D) helium.
E) none of these

Question 72

A certain radioactive isotope placed near a Geiger counter registers 120 counts per minute. If the half life of the isotope is one day, what will the count rate be at the end of four days?

A) 5 counts/min
B) 30 counts/min
C) 10 counts/min
D) 7.5 counts/min
E) 15 counts/min

Question 73

When a gamma ray is emitted by a nucleus, the nucleus then has less

A) energy.
B) charge.
C) both of these
D) neither of these

Question 74

Control is exercised in a nuclear reactor by

A) emitting fast neutrons with a moderator.
B) absorbing excess neutrons with control rods.
C) both of these
D) none of these

Question 75

The half-life of a radioactive substance is INDEPENDENT of

A) the age of the substance.
B) the number (if large enough) of atoms in the substance.
C) the temperature of the substance.
D) whether the substance exists in an elementary state or in a compound.
E) all of these

Question 76

A sample of relatively active radioactive material is somewhat

A) cooler than the environment.
B) warmer than the environment.
C) neither really

Question 77

When a nucleus emits a beta particle, its atomic number

A) decreases by 2.
B) increases by 2.
C) decreases by 1.
D) increases by 1.
E) none of these

Question 78

Which element has the smaller critical mass; U-235 that releases 2.5 neutrons per fission, or Pu-239 that releases 2.7 neutrons per fission?

A) U-235
B) Pu-239
C) Both would have the same critical mass.

Question 79

Hydrogen is a first-rate fuel for

A) nuclear reactions.
B) chemical reactions.
C) both of these
D) neither of these

Question 80

The atomic mass number of an element is the same as the number of its

A) protons.
B) nucleons.
C) neutrons.
D) none of these