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A radioactive elem..

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earth science
how does radioactive decay provide heat energy within the earth

chemistry
a radioactive substance decays 10% in 5 days. The amount remains after 20 days?

science
How can radioactive dating help determine the absolute age of a rock (or rock layer)?

Chem
The decay constant for a radioactive isotope is 7.82 x 10-6 /y. What is the half-life of this isotope in years?

earth
how Earth would be different today, if it contained no radioactive material

Physics
How many half-lives are required for the number of radioactive nuclei to decrease to 1/10^4 of the initial number?

Math
Find the half-life (in hours) of a radioactive substance that is reduced by 10 percent in 5 hours.

chem
what changes in atomic number and mass number occur in a positron emmision of radioactive decay?

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

math
A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

Chemistry
A 208 g sample of sodium-24 decays to 13.0 g of sodium-24 within 60.0 h. What is the half-life of this radioactive isotope?

Environmental Science 11th grade
If half of a quantity of radioactive material decays in 10 years, in another 10 years?

Health
What safety and health problems are associated with storing radioactive waste in deep geological repositorites?

Pre Calculus
If a 25 mg sample of radioactive material decays to 18.4 mg in 5 years, how long will it take the sample to decay to 20.5 mg?

math calculus
Find the half-life (in hours) of a radioactive substance that is reduced by 30 percent in 40 hours.

chemistry
If you accidentally spill phosphorus-32 onto your shoe, how long would it take before 99.9 of the radioactive material has decayed so that you can safely wear the shoes again?

Chemistry Numerical
The half life period of a radioactive element is 27.96 days. Calculate the time taken by a given sample to reduce to 1/8th of its initial activity

AP Chemistry
Which of the following is true about lanthanides? A. they are all radioactive B. they are highly electropositive C. they are very common elements D. they have low melting and boiling points

Pre calc
If 250 mg of a radioactive element decays to 200 mg in 48 hours, find the half-life of the element

chemistry
Which radioactive emanations have a charge of -1? beta particles alpha particles gamma rays neutrons

Chemistry
A radioactive element has a half-life of 6.41 days. What percent of the original sample will be left after 15.0 days?

Radioactivity
Iodine-131 is a radioactive isotope. After 8.00 days, 50.2% of the sample remains. What is the half life of 131-I?

Chemistry
A certain radioactive element has a half life of 1 h. If you start with a 1-g sample of the element at noon, how much is left at 3:00 PM? At 6:00PM? At 10:00 PM?

chemistry
a radioactive material is undergoing nuclear decay. After 40 minutes, 25% of the sample remains. What is the half-life of the sample

Calc
Radioactive radium () has a half-life of 1599 years. What percent of a given amount will remain after years?

physics
If a radioactive isotope has a half-life of 1 year, how much of the original sample will be left at the end of the 2nd year?

Physics
A radioactive substance decays from 2.0kg to 1.6kg in 156 days. What is the decay constant and the half life of the substance?

Physics
A radioactive substance decays from 2.0kg to 1.6kg in 156 days. How much will be left after 201 days?

physics
The half-life of a certain radioactive isotope is 32 hours.What fraction of the sample would remain after 16 hours?(a)0.50(b)0.25(c)0.62(d)0.71

isd muscat
after two hours 1/16th of the radioactive isotope remains undecayed.half life of the isotope is

Chemistry
Iodine 131 is a radioactive isotope. After 4.00 days, 70.8% of a sample of 131I remains.What is the half life of 131I?

Pre-Calc
A radioactive isotope has a half life of 8.1 days. If the sample starts with 25 grams, how much will there be after 90 days?

chemistry
The half-life of C14 radioactive is 5760 yr. After how much time will 200 mg C14 sample be reduced to 25 mg?

science
Can someone help me find two specific reasons why radioactive dating/geology are evidence for evolution. I've read many articles online but i do not really understand the whole concept.

science
the threat of global warming is mainly associated with ? 1 radioactive wastes 2 use of hydroelectric energy 3 burning of fossil fuels 4 thermal pollution of lakes and rivers

ALGEBRA
You have 480 grams of a radioactive kind of tin. If its half-life is 10 days, how much will be left after 30 days?

Science
if a radioactive isotope has a half-life of one year, how much of the original sample will be left at the end of the second year?

Science
if a radioactive isotope has a half-life of one year, how much of the original sample will be left at the end of the second year?

Math
An unknown radioactive substance has a half-life of 124 years. How long will it take a 67 grams sample to degrade to 18 grams?

Algebra
A radioactive kind of nitrogen has a half life of 10 minutes. If you start with 64 grams of the substance, how much will be left after 20 minutes?

Algebra 2
A particular radioactive element has a half life of 10.0 days. How much is left after 30.0 days if the sample started with 345g?

Chemistry
A particular radioactive element has a half life of 10.0 days. How much is left after 30.0 days if the sample started with 345g?

math algebra
The amount A, of 70 grams of a certain radioactive material remaining after t years can be found by the equation A=70(0.62)^t. When will 10 grams remain?

Chemistry
Thinking about the uses of radioactive isotopes, which statement is true? A. The iodine isotope, I-27, is used to diagnose thyroid disorders. B. Radiation may be detected because it ionizes the atoms it affects. C. It’s clearly understood that irradiating food kills bacteria...

Science
I'm kinda in a rush but take your time!Thx! 1.What was Henri Becquerel studying when he accidentally discovered radioactivity? A.photography B.properties of black light C.properties of X-rays D.solar energy 2.When Marie Curie isolated uranium from pitchblende, she realized ...

algebra
Scientists can determine the age of ancient objects by a method called radio carbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope 14C of carbon with a half-life of about 5710 years. Vegetation absorbs carbon dioxide ...

Chemistry
The nuclide 12 N 7 is unstable. What type of radioactive decay would be expected??? my guess is either gamma or beta. are either of those correct?

math
Radioactive radium has a half-life of approximately 1599 years. What percent of a given amount remains after 100 years?

math
Radioactive radium has a half-life of approximately 1599 years. What percent of a given amount remains after 100 years?

math
The decay of 333 mg of a radioactive substance is given by A(t) = 333e-0.024t, where t is time in years. Find the amount left after 17 years.

Physics
In the radioactive formula 235 U → 235 Np + X, what does X represent 92 93 A. An Alpha Particle B. A positron C. An electron D. A gamma ray Please help ASAP!!! Thank you :D

Science
If a 20 gram sample of a radioactive substance has a half-life of 6000 years, how many grams would be present after 18000 years?

Science
It can be inferred from the passage that radioactive dating is important for estimating the age of A) all known meters B) all existing planets C) the earth D) the trees

College Calculus
A radioactive substance has a half-life of 27 years. Find an expression for the amount of the substance at time t if 20 grams were present initially.

science
I need a picture that describes radioactive decay, fussion and fision. Someone said that they would give me a link earlier but they didnt. Thank you! This website helps me out so much.

chemistry
use logic and simple math to determine how long it will take for a sample of potassium- 42 to decay from 8mg to 0.25mg if the half-life of this radioactive isotope is 124 hours

Chemistry
Tc-99 is a radioactive isotope that decays by beta emission and is used by radiologists in the diagnosis of liver disease. Its decay behavior is shown by the activity-time table. What is its half-life?

chemistry
I am having trouble understanding what the concept is for writing these out. Write a balanced nuclear equation for the alpha decay of each of the following radioactive isotopes: curium-243, 22589Ac

Biology-check my answer
Hershey and Chase used the 35S isotope to label proteins. How does this isotope differ from the 32S isotope found in greatest natural abundance, and why did they choose 35S instead of 32S? A)35S has more protons than 32S; Hershey and Chase used it because it has a greater mass...

Physics
A certian radioactive isotope has a half-life of 1 hour. If you start with 1 gram of the material at noon, how much of the original isotope will the sample contain at 3 pm? At 6 pm? At 10 pm?

math
if the rate for radioactive decay for a substance is r=-.0063 and time is being measured in days how do you find the half-life of the substance to the nearest hour?

physics
Pick the radioactive isotope in each set 23/11 na or 20/9 f explain why a)its atomic number is greater than 83 b)it has fewer n than p in the nucleus c)it is an odd-odd nuclide none of the above

PHYICS
Pick the radioactive isotope in each set 14/7 N OR 23/13 AL EXPLAIN A)its atomic number is greater than 83 B)it has fewer n than p in the nucleus C)it is an odd-odd nuclide none of the above

math
Show that if a radioactive substance has a half life of T, then the corresponding constant k in the exponential decay function is given by k=-ln(2)/T I'm confused about how to show that that is true.

Chemistry
The radioactive nuclide 18F decays by first order kinetics with a half life of 1.83 hr. How many hours will it take for 68.5% of a give quantity of 18F to decay?

Math
the half life of a radioactive substance is one day. You have 100 grams. how much of the substance would be left after a week?

Algebra 2
A radioactive substance decays at a rate of y = ae^-0.1483t, where t in in hours. Find the half-life of the substance. How do I solve this problem if I am only given the constant.

Pre-Calc
Tritium, a radioactive isotope of hydrogen, has a half-life of 12.4 years. Of an initial sample of 69 grams, how much will remain after 75 years?

Alg2
Radioactive iodine is used to determine the health of the thyroid gland. It decays according to the equation y=ae -0.0856t where t is in days. Find the half-life of this substance. Round to the tenths place.

Alg2
Radioactive iodine is used to determine the health of the thyroid gland. It decays according to the equation y=ae -0.0856t where t is in days. Find the half-life of this substance. Round to the tenths place.

American Constitutional Law
The Low-Level Radioactive Waste Policy Amendments Act established the following as incentives to the states. A. Financial B. Access C. Take Title D. All of the above Is it D?

Calculus
A certain radioactive material decays exponetially. The percent, P, of the material left after t years is given by P(t)= 100(1.2)^-t a)Determine the half life of the substance

phyics
Pick the radioactive isotope in each set. 23/11 20/9 Explain your choice. a)its atomic number is greater than 83 b)it has fewer n than p in the nucleus c)it is an odd-odd nuclide none of the above

Physics
In the radioactive formula, 235 U → 235 Np = X, what does X represent 92 93 A. An alpha Particle B. A positron C. An electron D. A gamma ray Please help ASAP!!! Thank you very much!!

College algebra
The radioactive element has a half-life of about 28 years and sometimes contaminates the soil. After 47 years, what percentage of a sample of the elements remain?

physics
Radon 86222Rn is a radioactive gas with a half-life of 3.82 d. If there are initially 400 decays/s in a sample, how many radon nuclei are left after 2 d ? Please help, I don't understand how to do this.

AP Chem ---
If a radioactive nucleus alpha decays to yield a sodium24 nucleus in 14.8 hours, what was the identity of the original nucleus? Nuclear equation?

chemistry
What are some applications of Nuclear Chemistry in Medicine? So far I've found - X-rays - Radioactive tracers - Gamma radiation can be used to treat cancer and other diseases

college
The average number of radioactive particles passing through a counter during 1 millisecond in a lab experiment is 4. What is the probability that more than 2 milliseconds pass between particles?

statistics
The average number of radioactive particles passing through a counter during 1 millisecond in a lab experiment is 4. What is the probability that more than 2 milliseconds pass between particles?

Physical Science- Help Please!
Suppose that you are given a 100 gram sample of a radioactive substance with a half-life of 32 days. How many grams will be left after 192 days?

Chem
Suppose that you start with 1000000 atoms of a particular radioactive isotope. how many half-lives woruld be required to reduce the number of undecayed atoms to fewer than 1000?

Elem. Ed.
b and c, don't you think? the teacher explains and the children practice what has been explained my experience leads to me to the conclusion that actual practice is the best learning technique. I vote for c. sounds good Can you help me with this question? An instructional ...

Physical Science
I'm still working on getting a fireman to come out to the school to demonstrate a radioactive detector. No luck so far. This is for a project on Marie Curie. Any other suggestions would be greatly appreciated.

Physical Science
The heat of volcanoes and hot springs comes from trace amounts of radioactive minerals found in the Earth's interior. Why isn't the same rock at the Earth's surface warm?

Elem. Ed.----- I Need Help!!!
Can you help with this question? 1. Charts do not: A. offer an opportunity for shared experiences. B. allow the print to stand out. C. capture the children's attention. D. teach children to read at a very early age. I know charts (A) offer opportunities for shared experiences,...

Elem. ED.
Art and math are being integrated when students: 1. draw more than 1 picture on a page. 2. use rectangular paint pots. 3. identify geometric shapes when composing a picture. 4. insist on using the same materials as their peers. Is the 3rd answer correct? "identifying geometric...

physics
Suppose 32000 radioactive nuclei are in a sample. About how many remain after two days if the half-life is 22 hrs? What is the initial activity of the sample in decays per minute?

Chem
Radioactive 24Na with a half-life of 14.8 hours is injected into an animal in a tracer experiment. How many hours will it take for the radioactivity to fall to 12.5% of its original intensity? I am confused on what number to start with

Physics
Can someone give me an example of how to use this formula: 15.Obtain three half-life (T0.5) times from the graph. Average them.(T0.5)av. Or is there a web site i can go to that shows all steps to using pennies for radioactive decay experiment? .

chem
19. A radioactive nucleus decays to yield a bismuth-211 nucleus and an alpha particle. What was the identity of the original nucleus? Show the nuclear equation that leads you to this answer.

Science
How much of a radioactive material with a half-life of 12,000 years is left after 36,000 years of decay?

chm
An unknown radioactive substance has a half-life of 3.20 . If 34.8 of the substance is currently present, what mass was present 8.00 hours ago?

Exponential decay
Show that if a radioactive substance has a half life of T, then the corresponding exponential decay function can be written as y=y0e^kt

Chemistry
If a 40 gram sample of radioactive isotope was present at 4pm, but a 5 gram sample remained at 4:30 pm, what is the half-life in minutes?

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