CH 33
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 be the count rate at the end of four days?
7.5 counts/min
When U-239 emits a beta particle, the resulting nucleus has
93 protons
Which of the following isotopes is radioactive?
Carbon-14
A quark is a fundamental particle
all of the above
In order for an atom to decay to an element that is one greater in atomic number, it can emit
all of the above
In a smoke detector americium (A = 95) transmutes to neptunium (A = 93) by
alpha emission.
Radium (A = 88) transmutes to radon (A = 86) by
alpha emission.
Pure elements can be transformed into entirely different elements by
both of these
Which is heated in its interior by nuclear processes?
both of these
Carbon-14 is produced in the atmosphere principally by
cosmic-ray bombardment.
Cosmic rays originate in the
cosmos.
The most harmful radiations are those that
damage living cells.
Once an alpha particle is outside the nucleus it is
electrostatically repelled.
Some charged particles in a bubble chamber are seen to move in spirals due to
energy dissipation.
Which radiation has no association with electric charge?
gamma
Which will NOT bend when moving in a magnetic field?
gamma ray
When the hydrogen isotope tritium-3 emits a beta particle, it becomes an isotope of
helium.
X-rays may be correctly regarded as
high frequency radio waves
A hydrogen atom that emits an alpha particle is a routine occurrence in
impossible.
When a nucleus emits a beta particle, its atomic number
increases by 1.
Generally speaking, the larger a nucleus is, the greater its
instability.
The natural background radiation we personally encounter is
more than half.
The sources of both X-rays and gamma rays are
neither of these
For an isotope with a half-life of one day, at the end of three days the amount that remains is
one-eighth.
Carbon dating requires that the object being tested contain
organic material.
A nucleon is either a
proton or a neutron.
The main source of Earth's natural heat is
radioactivity in Earth's interior.
Radiation dosage is commonly measured in
rads.
Which device is used primarily to detect nuclear radiation?
scintillation counter
Part of a wooden ancient ship is found to be 1/3 as radioactive as wood freshly cut from a tree. The age of the ship is likely about
three times carbon-14's half-life.
Gamma rays are emitted by way of
transitions within the atomic nucleus.
A sample of highly-radioactive material is somewhat
warmer than the environment.
The half-life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about
17,200 years.
A certain radioactive isotope placed near a Geiger counter registers 160 counts per minute. Eight hours later, the counter registers 10 counts per minute. What is the half-life of the isotope?
2 hours