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- Half-life and activity
To obtain the most precise value of BE from the equation
, we should take into account the binding energy of the electrons in the neutral atoms. Will doing this produce a larger or smaller value for BE? Why is this effect usually negligible?
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Problems&Exercises
Data from the appendices and the periodic table may be needed for these problems.
An old campfire is uncovered during an archaeological dig. Its charcoal is found to contain less than 1/1000 the normal amount of
. Estimate the minimum age of the charcoal, noting that
.
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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?
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(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.
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Show that the activity of the
in 1.00 g of
found in living tissue is 0.250 Bq.
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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?
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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?
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(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.)
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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?
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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?
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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.
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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?
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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?
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Questions & Answers
Discuss the differences between taste and flavor, including how other sensory inputs contribute to our perception of flavor.
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
Faith
While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
Kamara
which drugs can we use for ulcers
Omeprazole
Cimetidine / Tagament
For the complicated once ulcer - kit
Patrick
what is the function of lymphatic system
to drain extracellular fluid all over the body.
asegid
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include:
1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
asegid
to transport fluids fats proteins and lymphocytes to the blood stream as lymph
Adama
Anatomy is the identification and description of the structures of living things
Kamara
what's the difference between anatomy and physiology
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
how does the stomach protect itself from the damaging effects of HCl
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
function of digestive system
function of digestive
Ali
what is the normal body temperature
please why 37 degree selcius normal temperature
Mark
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body
the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
Stephanie
anaemia is the decrease in RBC count hemoglobin count and PVC count
Eniola
what is the pH of the vagina
how does Lysin attack pathogens
Diya
I information on anatomy position and digestive system and there enzyme
anatomy of the female external genitalia
Organ Systems Of The Human Body (Continued)
Organ Systems Of The Human Body (Continued)
what's lochia albra
Kizito
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Source:
OpenStax, College physics for ap® courses. OpenStax CNX. Nov 04, 2016 Download for free at https://legacy.cnx.org/content/col11844/1.14
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