Chapter 32-34 (FINAL EXAM)

Which of the following isotopes is radioactive?

A) Carbon‐14

Control is exercised in a nuclear reactor by

A) absorbing excess neutrons with control rods.

Which experiences the greatest electrical force in an electric field?

A) alpha particle

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

A) energy.

Which radiation has no electric charge associated with it?

A) gamma rays

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

A) has a short half‐life.

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

A) instability.

n 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.

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

A) nucleons.

Electric forces within an atomic nucleus tend to

A) push it apart.

The high temperature of the Earthʹs interior is due mostly to

A) radioactivity.

Compared to the wavelengths of visible light, the wavelengths of matter waves are relatively

A) small.

Alpha particles are repelled by atomic nuclei because A) they both have the same sign of electric charge. B) the force between the alpha particle and the atomic nucleus is opposite to an attractive force. C) of the repelling interaction between an alpha particle and the atomic nucleus. D) closeness of each to each other is not permitted. E) none of these

A) they both have the same sign of electric charge.

Most alpha particles fired at a gold foil pass through undeflected because the A) net charge of the gold atoms is zero. B) atoms of gold, like any others, are mostly empty space. C) electric field is zero inside the gold. D) gold atoms, unlike most other metal atoms, are relatively far apart. E) none of these

B) atoms of gold, like any others, are mostly empty space

In the fissioning of uranium, a chain reaction is caused by

B) ejected neutrons.

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

B) element.

Between nuclear fission and nuclear fusion, radioactive by‐products are more characteristic of nuclear

B) fission.

The most abundant element in the universe is

B) hydrogen.

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

B) increases.

A nucleon has the least mass in the nucleus of

B) iron.

An excited hydrogen atom is capable of emitting radiation of A) 3 frequencies. B) many more than 3 frequencies. C) a single frequency.

B) many more than 3 frequencies.

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

B) sphere

Orbital electrons do not spiral into the nucleus because of

B) the wave nature of the electron.

A hypothetical atom has four distinct energy states. Assuming all transitions are possible, how many spectral lines can this atom produce?

C) 6

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

C) 91.

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

C) big enough.

The origin of cosmic rays is the

C) cosmos

When a nucleus emits a positron, its atomic number

C) decreases by 1.

X‐rays are similar to

C) gamma rays.

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

C) greater than one.

Detonation of a fusion‐type hydrogen bomb is started by

C) igniting a small fission bomb.

In both fission and fusion, mass

C) is converted to kinetic energy.

Uranium‐235, uranium‐238 and uranium‐239 are different

C) isotopes.

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

C) less mass.

The Bohr model of the atom is akin to a

C) miniature solar system.

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

C) one‐quarter.

An excited atom decays to its ground state and emits a photon of green light. If instead the atom 9) decays to an intermediate state, then the light emitted could be

C) red.

The main reason electrons occupy discrete orbits in an atom is because

C) the circumference of each orbit is an integral multiple of electron wavelengths.

The mass of an atomic nucleon is nearly

C) two thousand times the mass of an electron.

When radium (A = 88) emits an alpha particle, the resulting nucleus has atomic number

D) 86.

A nucleon is either

D) a proton or a neutron.

The function of graphite in the first atomic reactor was to

D) absorb fast neutrons.

Different isotopes of an element have different numbers of

D) neutrons.

Most of the radioactivity we personally encounter comes from

D) the natural environment.

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?

E) 7.5 counts/min

The nucleus with the most tightly bound nucleons is

E) iron.

Fusing two helium nuclei yields a net

release of energy.

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

C) less than 1%

Quantization of electron energy states in an atom is better understood in terms of the electronʹs A) wave nature. B) particle nature. C) neither of these

A) wave nature.

When Rutherford had a stream of alpha particles hit a gold foil, most of the particles A) went almost straight through B) spiraled. C) stopped. D) bounced back.

A) went almost straight through