Phys6C Ch41 Nuclear Physics and Radioactivity

Equation of nuclear fusion in the Sun?

4p + 2e- --> He + 2v + E

Except for the lightest nuclei, the average binding energy per nucleon is about: 4 MeV. 6 MeV. 10 MeV. 8 MeV. 12 MeV.

8 MeV

All nuclei of a given element have the same number of neutrons. T or F?

False

The proton is slightly more massive than the neutron. T or F?

False

Origin of sunshine?

Gravity attracts protons at the center of newly formed Sun. These protons repel each other by Coulomb force but are squeezed so strongly by gravitational radiation. The strong force eventually takes over and begins to fuse 4 protons into a He nucleus. The loss of mass becomes solar energy.

If an atom's atomic number is given by Z, its atomic mass by A, and its neutron number by N, which of the following is correct? N = Z - A N = A + 2Z N = A - Z N = A + Z N = 2A + Z

N = A - Z

Which of the following statements concerning the nuclear force is FALSE? The nuclear is one of only four known types of forces in nature. The nuclear force is very weak and much smaller in relative magnitude than the electrostatic and gravitational forces. The nuclear force is very short-ranged. The nuclear force is attractive and not repulsive. The nuclear force acts on both protons and neutrons.

The nuclear force is very weak and much smaller in relative magnitude than the electrostatic and gravitational forces.

The symbols Z, A, and N respectively stand for: atomic mass number, proton number, nucleon number. atomic number, neutron number, atomic mass number. atomic number, atomic mass number, neutron number. neutron number, atomic mass number, atomic number. atomic mass number, atomic number, neutron number.

Z = atomic number A = atomic mass number N = neutron number.

A β- decay occurs in an unstable nucleus when: a neutron is converted to an alpha particle by the weak force. a neutron is converted to a beta particle by the weak force. a proton is converted to an electron by the strong force. a neutron is converted to a proton by the weak force. a proton is converted to a neutron by the strong force.

a neutron is converted to a proton by the weak force.

A β+ particle is also known as: a photon. a proton. an electron. a helium nucleus. a positron.

a positron.

A β- particle is also known as: a photon. a proton. a positron. an electron. a helium nucleus.

an electron

The type of detector that uses a magnetic field to curve charged particles is a: scintillation counter. bubble chamber. cloud chamber. spark chamber. Geiger tube.

bubble chamber.

When an unstable nucleus decays by emitting an alpha particle, the atomic number of the nucleus: increases by 2. decreases by 4. decreases by 2. increases by 4. remains unchanged.

decreases by 2.

Atoms with the same atomic number but with different numbers of neutrons are referred to as: positrons. nuclides. isotopes. nucleons. none of the given answers

isotopes.

Heavier stable nuclei tend to have: no trend in relative number of neutrons and protons. the same number of neutrons and protons. more protons than neutrons. more neutrons than protons. half as many protons as neutrons.

more protons than neutrons.

The difference in the masses of a neutron and proton is: equal to the mass of an electron. one. more than the mass of an electron. less than the mass of an electron. zero.

more than the mass of an electron. n --> p + e- + neutrino

Compared to the electrostatic force, the nuclear force between adjacent protons in a nucleus is: only slightly weaker. about the same size. much weaker. only slightly larger. much larger.

much larger

In beta decay, it is found that the energy of the emitted electrons varies and is always less than what is calculated on the basis of the parent and daughter nuclei. This is evidence for the existence of another particle called the: quark. neutrino. meson. positrons. gluon.

neutrino

In all three types of radioactive decay, what value is conserved in addition to electric charge, energy, and momentum? nucleon number neutron number neutron number atomic number none of the given answers

nucleon number

The mass number is equal to the number of what particles in the nucleus? positrons. nucleons neutrons electrons protons

nucleons

The atomic mass unit is defined as: the mass of an electron. one twelfth the mass of a carbon-12 atom. the mass of a hydrogen-1 atom. the mass of a proton. the mass of a neutron.

one twelfth the mass of a carbon-12 atom.

When nucleons join to form a stable nucleus, energy is: absorbed. destroyed. released. not transferred. either absorbed or released depending on nucleons involved.

released

Beta rays can penetrate: a piece of paper. air only. several millimeters of aluminum. several centimeters of lead. several meters of iron.

several millimeters of aluminum.

Cloud chambers have been replaced by bubble chambers because: gamma rays are visible in bubble chambers, but not in cloud chambers. the density of fluids is greater than the density of vapors. the radioactive clouds were too dangerous to work with. bubble chambers tend to be larger and more expensive.

the density of fluids is greater than the density of vapors.

When a gamma ray is emitted from an unstable nucleus, the number of neutrons drops by one and the number of protons increases by one. there is no change in either the number of neutrons or the number of protons. the number of neutrons and the number of protons drop by two. the number of protons drops by one and the number of neutrons increases by one. none of the given answers

there is no change in either the number of neutrons or the number of protons.