Nuclear Chemistry Unit test review

What effect does supercritical mass have on a nuclear reaction?

The reaction rate increases.

The reaction produces less energy.

The reaction involves increased fusion.

The reaction produces fewer neutrons.

The reaction rate increases.

Which statement about the half-life of a radioactive sample is true?

It is an exact measure of the decay of an individual atom.

It measures the tendency of a radioisotope to decay radioactively.

It is affected by the concentration of the radioactive substance that is present.

It can be calculated based on neutron number.

It measures the tendency of a radioisotope to decay radioactively.

Which type of reaction does this diagram represent?

mc008-1.jpg

a chain reaction that is caused by nuclear fission

a chain reaction that is caused by nuclear fusion

a decrease in energy that is caused by nuclear fission

an increase in energy that is caused by nuclear fusion

a chain reaction that is caused by nuclear fission

The alpha decay of a radioactive nuclide (X) emits a He-4 nucleus and produces an isotope of 235/92 U. What is X?

235/91 Pa

235/93 Np

236/92 U

239/94 Pu

239/94 Pu

Which best describes nuclear fusion?

A nucleus spontaneously splits and absorbs energy.

Two nuclei spontaneously combine and absorb energy.

A nucleus collides with a neutron and splits, releasing energy.

Nuclei combine to form a heavier nucleus, releasing energy.

Nuclei combine to form a heavier nucleus, releasing energy.

What occurs during one half-life?

Half of a daughter isotope undergoes radioactive decay to form a parent isotope.

Half of a parent isotope undergoes radioactive decay to form a daughter isotope.

All of a daughter isotope undergoes radioactive decay to form a parent isotope.

All of a parent isotope undergoes radioactive decay to form a daughter isotope.

Half of a parent isotope undergoes radioactive decay to form a daughter isotope.

A radioactive nuclide that is used for radiation therapy for cancer has 33 neutrons and a mass number of 60. Which is the correct symbol for this nuclide?

27/60 Co

33/60 Co

60/33 Co

60/27 Co

60/27 Co

Potassium-40 has a half-life of 1.277 x 10^9 years. After 1.022 x 10^10 years, how much potassium-40 will remain from a 500.3-g sample?

approximately 1.95 g

approximately 3.91 g

approximately 62.54 g

approximately 71.47 g

approximately 1.95 g

Consider the three equations below.

14/7 N + 1/1 H → 15/8 O

4/2 He + 4/2 He → 8/4 Be

28/14 Si + 7 4/2 He → 56/28 Ni

Which statement do these reactions best support?

Beta decay occurs only in certain atoms.

Alpha decay occurs only in certain atoms.

Chain reactions play important roles in the process of nuclear fission.

Nuclear fusion plays an important role in making elements that are heavier than helium.

Nuclear fusion plays an important role in making elements that are heavier than helium.

Which issue poses the greatest long-term challenge in the development of new nuclear power plants?

controlling carbon dioxide emissions

storage of radioactive waste

controlling fission reactions

mining of uranium

storage of radioactive waste

A shield of material that reflects neutrons is placed around a radioactive sample. Which change in the nuclear reaction is most likely to happen?

A chain reaction will be sustained in a subcritical mass.

The chain reaction in a critical mass will stop.

A chain reaction will occur at a constant rate in a critical mass.

The chain reaction in a supercritical mass will slow down.

A chain reaction will be sustained in a subcritical mass.

If an unshielded sample of radioactive material emits alpha particles, what effect will it have on a person sitting in the next room? (Assume the wall between rooms is composed of concrete.)

None, because the wall will block the radiation.

The radiation will travel through the person's body.

None, because the radiation will bounce off the person's body.

The radiation will be totally absorbed by the person's body.

None, because the wall will block the radiation.

After a radioactive atom decays, it is the same element that it was before with no measurable change in mass. Which kind of decay has occurred, and how do you know?

alpha decay because alpha particles have no mass

beta decay because this kind of decay cannot change one element into another

alpha decay because it creates a new isotope of the same element

gamma decay because photons have no mass

gamma decay because photons have no mass

Which procedure will most increase the energy output of a nuclear reactor?

exposing the core to the outside world

removing fissile material from the core

decreasing the amount of steam produced

raising the control rods out of the reactor

raising the control rods out of the reactor

Which particles that make up an atom are involved in nuclear reactions?

protons only

protons and neutrons

electrons only

electrons and neutrons

protons and neutrons