Review Questions: Nuclear Physics
Answers
1) Nuclei normally contain
a) protons only
b) neutrons
c) both protons and neutrons
d) protons, neutrons and electrons
2) Atomic number refers to
a) the number of neutrons in a nucleus
b) the number of protons in a nucleus
c) the number of protons plus electrons
d) the total number of protons and neutrons
3) Mass number refers to
a) the number of neutrons in a nucleus
b) the number of protons in a nucleus
c) the number of protons
d) the total number of protons and neutrons
4) Isotopes have in common
a) the same number of protons
b) the same number of neutrons
c) the same atomic weight
d) none of these
5) U- 235 contains
a) 92 protons and 235 neutrons
b) 235 protons and 92 neutrons
c) 92 protons and 143 neutrons
d) 143 protons and 92 neutrons
6) A nuclear force is assumed to exist in order to
a) keep electrons orbiting the nucleus
b) explain radioactivity
c) allow for fission to occur
d) to keep the nucleus stable in spite of Coulomb repulsion
7) Helium nuclei emitted in radioactive processes are known as
a) alpha particles
b) beta particles
c) gamma rays
d) quarks
8) A C-14 nucleus decays by emitting an electron to become the nucleus of
a) C-12
b) N-14
c) C-13
d) N-13
9) A U(92,238) decays by alpha decay to a nucleus containing how many protons?
a) 88
b) 92
c) 90
d) 93
10) The half-life of a radioactive isotope is one day. How much of the original material will be left after two days?
a) none
b) one-half
c) one-fourth
d) all
11) Uranium is found to be accompanied by an equal number of daughter nuclei in some ancient rocks. If the half life of the uranium is 4.5x10^9 years, how old (in years) are the rocks?
a) 2.25x10^9
b) 9x10^9
c) 4.5x10^9
d) none of these
12) Particles released in radioactive decay
a) can cause considerable biological damage
b) cannot cause biological damage
c) can cause biological damage only in sick people
d) are very slow moving
13) A chain reaction refers to
a) radioactive decay
b) the fusion process
c) neutrons produced in one fission continue to produce more fission
d) alpha particles creating nuclear reactions
14) The combining of two light nuclei to produce a heavier one is called
a) fission
b) fusion
c) radioactive decay
d) a chain reaction
15) Nuclear fission is the process whereby
a) small nuclei are combined to form a large nucleus
b) nuclei are caused to boil
c) radioactivity was discovered
d) large nuclei split apart
16) The electromagnetic force compared to the nuclear force is
a) stronger
b) weaker
c) of the same strength
d) nonexistent
17) How would you expect an unstable nucleus of Zn-80 to decay?
a) alpha decay
b) beta-plus decay
c) beta-minus decay
d) electron capture
Reasoning: Zn-80 means the mass number is 80. This isotope has too many neutrons. We know this by comparing it to the stable isotope of Zn which has 35 neutrons. (Check the peiodic table and verfy this number). For Zn-80, the number of neutrons is 80-30 = 50. Too many n's result in beta-minus decay.
18) Which of the forces is responsible for holding nucleons together to form nuclei?
a) electric
b) magnetic
c) strong
d) gravity
Reasoning: Nuclear force is also called the "strong" force as well.
19) Which of the following is not one of the four forces in nature?
a) inertial
b) strong
c) weak
d) electromagnetic
20) What is the most likely decay mode of Na-20?
a) alpha decay
b) beta-plus decay
c) beta-minus decay
d) electron capture
21) The source of sun’s energy is
a) thermonuclear fusion reactions within the sun
b) thermonuclear fission reactions within the sun
c) thermochemical reactions at the core of the sun
d) the beta decay reactions within the sun
22) In heavy and stable nuclei the number of protons compared to the number of neutrons is
a) more
b) less
c) the same
d) ..heavy nuclei contain only protons and no neutrons