-
Home
- College physics
- Radioactivity and nuclear physics
- Half-life and activity
A
source is labeled 4.00 mCi, but its present activity is found to be
Bq. (a) What is the present activity in mCi? (b) How long ago did it actually have a 4.00-mCi activity?
Got questions? Get instant answers now!
(a) Calculate the activity
in curies of 1.00 g of
. (b) Discuss why your answer is not exactly 1.00 Ci, given that the curie was originally supposed to be exactly the activity of a gram of radium.
(a) 0.988 Ci
(b) The half-life of
is now better known.
Got questions? Get instant answers now!
Show that the activity of the
in 1.00 g of
found in living tissue is 0.250 Bq.
Got questions? Get instant answers now!
Mantles for gas lanterns contain thorium, because it forms an oxide that can survive being heated to incandescence for long periods of time. Natural thorium is almost 100%
, with a half-life of
. If an average lantern mantle contains 300 mg of thorium, what is its activity?
Got questions? Get instant answers now!
Cow’s milk produced near nuclear reactors can be tested for as little as 1.00 pCi of
per liter, to check for possible reactor leakage. What mass of
has this activity?
Got questions? Get instant answers now!
(a) Natural potassium contains
, which has a half-life of
y. What mass of
in a person would have a decay rate of 4140 Bq? (b) What is the fraction of
in natural potassium, given that the person has 140 g in his body? (These numbers are typical for a 70-kg adult.)
Got questions? Get instant answers now!
There is more than one isotope of natural uranium. If a researcher isolates 1.00 mg of the relatively scarce
and finds this mass to have an activity of 80.0 Bq, what is its half-life in years?
Got questions? Get instant answers now!
has one of the longest known radioactive half-lives. In a difficult experiment, a researcher found that the activity of 1.00 kg of
is 1.75 Bq. What is the half-life in years?
Got questions? Get instant answers now!
You can sometimes find deep red crystal vases in antique stores, called uranium glass because their color was produced by doping the glass with uranium. Look up the natural isotopes of uranium and their half-lives, and calculate the activity of such a vase assuming it has 2.00 g of uranium in it. Neglect the activity of any daughter nuclides.
Got questions? Get instant answers now!
A tree falls in a forest. How many years must pass before the
activity in 1.00 g of the tree’s carbon drops to 1.00 decay per hour?
Got questions? Get instant answers now!
A 5000-Ci
source used for cancer therapy is considered too weak to be useful when its activity falls to 3500 Ci. How long after its manufacture does this happen?
Got questions? Get instant answers now!
Natural uranium is 0.7200%
and 99.27%
. What were the percentages of
and
in natural uranium when Earth formed
years ago?
Got questions? Get instant answers now!
The
particles emitted in the decay of
(tritium) interact with matter to create light in a glow-in-the-dark exit sign. At the time of manufacture, such a sign contains 15.0 Ci of
. (a) What is the mass of the tritium? (b) What is its activity 5.00 y after manufacture?
Got questions? Get instant answers now!
World War II aircraft had instruments with glowing radium-painted dials (see
[link] ). The activity of one such instrument was
Bq when new. (a) What mass of
was present? (b) After some years, the phosphors on the dials deteriorated chemically, but the radium did not escape. What is the activity of this instrument 57.0 years after it was made?
Got questions? Get instant answers now!
Questions & Answers
the study of living organisms and their interactions with one another and their environments
AI-Robot
HOW CAN MAN ORGAN FUNCTION
the diagram of the digestive system
allimentary cannel
Ogenrwot
They formed in two ways first when one sperm and one egg are splited by mitosis or two sperm and two eggs join together
Oluwatobi
Genetics is the study of heredity
Misack
how does twins formed?
Misack
discuss biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
list any five characteristics of the blood cells
Shaker
lack electricity and its more savely than electronic microscope because its naturally by using of light
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things
Ramadan
is organisms that are similar into groups called tara
Yamosa
in what situation (s) would be the use of a scanning electron microscope be ideal and why?
A scanning electron microscope (SEM) is ideal for situations requiring high-resolution imaging of surfaces. It is commonly used in materials science, biology, and geology to examine the topography and composition of samples at a nanoscale level. SEM is particularly useful for studying fine details,
Hilary
cell is the building block of life.
Got questions? Join the online conversation and get instant answers!
Source:
OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.