phys. final
In a decay of 90Th 232 by emission of an alpha particle, the daughter nucleus will be
88Ra228.
A nucleus undergoes radioactive decay, emitting a gamma ray. Which of the following statements is true?
Both daughter and parent nuclei have the same atomic number
Which of the following mechanisms can change the half-life of radioactive nuclei?
None of these.
What is the source of the energy released in nuclear reactions?
The conversion of mass to energy.
In nuclear fission,
a nucleus is split into two less massive nuclei.
In all nuclear reactions,
all of these
Energy released in a nuclear fission process is produced by
conversion of some mass to energy.
A "gamma" ray is
electromagnetic radiation
The energy radiated by the sun has as its primary origin energy produced by reactions.
fusion
The three types of nuclear radiation are
gamma, beta, alpha.
Generally, the number of neutrons present in nuclei that are fission fragments is ________ the number of neutrons of corresponding nuclei of stable isotopes.
greater than
The substance that comes from a nuclear reactor which can be used to generate power is
high-pressure steam.
When a nucleus undergoes alpha decay, the daughter element always has
less charge than the parent.
A deuterium nucleus and a tritium nucleus react to yield one alpha particle, a neutron, and energy. For this reaction, the sum of the masses of reaction products after the reaction is __________ the sum of the masses of particles before the reaction.
less than
Momentum and energy from focused laser beams can be used in nuclear fusion. This has an advantage over magnetic confinement reactors in that
light cannot be melted, so its pressure can confine the reaction
The primary reason that nuclear fusion has proven difficult to adapt for commercial power generation is that
nuclei repel each other due to their positive charges
The purpose of the moderator in a reactor is to
slow neutrons down so that they will be more likely to initiate fission reactions
Neutrons were discovered by James Chadwick by observing the behavior of
the collision after-effects of protons emerging from paraffin.
The number of protons in the nucleus of an atom determines
the density of the nucleus.
Consider two different samples of radioactive isotopes, one naturally occurring and the other artificially produced. If the samples have the same number of nuclei, then
the one with the shorter half-life is likely more dangerous.
In a nuclear reactor, "chain reaction" refers primarily to
the process by which the fission of one nucleus causes other nuclei to undergo fission.
A sample of U 235 that is below the critical mass will not sustain a chain reaction because
too many neutrons escape through the surface of the sample without initiating fission.
A feature of the nuclear reactor at Chernobyl that contributed to the magnitude of the accident there was that
water was used only as a coolant, not a moderator