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April 28, 2016

Search: half life

Number of results: 15,499

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?
January 6, 2013 by John

physical science
sodium-24 has a half life of 15 hours,how much of a 50 gram sample will be left after 60 hours
February 16, 2013 by sue moore

Algebra
An isotope has a half-life of 97 years. how much of a 19-gram sample is left after 150 years?
November 13, 2014 by Miles

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?
September 28, 2015 by Jessica

Science
The half-life of randon-222 is 8 days. What was the original mass if 6 grams remains after 24 days?
February 19, 2016 by Sarah

Calculus
An artifact was found with 63.8% of Carbon 14, how old is the mummy, assuming the half-life of Carbon 14 is 5730 years.
March 27, 2016 by Homework Help

algebra
Homer is giving some cookies to each of his three brothers. To the oldest, he gives half of the cookies and half a cookie. He then gives half of what is now left and half a cookie to his second brother. Finally, he gives half of what is now left and half a cookie to his second...
November 24, 2009 by john

Mathematics
If a man and a half finishes a job and a half within a day and a half, how many men can finish 3 jobs within 3 days. Please I need help, I am not so sure with my answer of 6. I would like to verify it. THANKS
June 25, 2013 by xavier

math
I asked the following the other day and received the following answer: Posted by Matthew on Sunday, March 17, 2013 at 11:03pm. A quantity of oxygen gas had 16.32 g of the radioactive isotope oxygen-19 in it. When measured exactly 10 minutes later, the amount of oxygen-19 was 0...
March 18, 2013 by Matthew

chemistry
The half-life of stronitum-90 is 28 years. How many grams of this nuclide in a 4.00g sample will remain after 112 years?
April 27, 2010 by Peter

Chemistry
The half-life of xe-133 is 126 hours. Starting with 250 mg, after 500 hours around how many mg remain?
May 22, 2010 by Lily

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?
October 8, 2010 by Jennifer

Chemistry
In 6.20 h a 100 g sample of ag 112 decays to 25 grams. what is the half life of ag 112. I think the answer is 3.10 but I'm not sure. Thanks in advance =)
June 15, 2011 by Jackie

chemistry
a radioactive material is undergoing nuclear decay. After 40 minutes, 25% of the sample remains. What is the half-life of the sample
August 27, 2011 by marjani

chemistry
If the radiicativr decay of nuclear explosion contains 90 Sr , with a half life of 28.1 years how long will it take for 99 of this radioaioot to decay
December 5, 2011 by devin

Calc
Radioactive radium () has a half-life of 1599 years. What percent of a given amount will remain after years?
April 15, 2012 by Pamela

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?
August 23, 2012 by Anonymous

Chemistry
Carbon-14 has a half-life of 5730 y. How much of a 144 g sample of a carbon-14 will remain after 1.719 (times) 10 4y?
December 11, 2012 by David

Chemistry
Carbon-14 has a half-life of 5730 y. How much of a 144 g sample of a carbon-14 will remain after 1.719 (times) 10 4y?
December 11, 2012 by David

physical science
cobalt-60 has a half-life of 5.26 years, how much of a 500 gram sample will be left after 21 years
February 16, 2013 by sue moore

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?
August 6, 2013 by Alice

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
September 22, 2013 by john

Chemistry
The half-life of 232Th is 1.4 * 10^10. Find the number of disintegrations per hour emitted by 1 mil of 232Th in 1 min.
April 10, 2014 by Nic

Chemistry
The half-life of Th-232 is 1.4E10. Find the number of disintegrations per hour emitted by 1 mol of Th-232.
April 10, 2014 by Nic

isd muscat
after two hours 1/16th of the radioactive isotope remains undecayed.half life of the isotope is
April 11, 2014 by saritha

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?
April 26, 2014 by Natalie

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?
November 3, 2014 by Jennifer

matg
Cobalt-60 has a half-life of about 5 years. How many grams of a 300 g sample will remain after 20 years? (Points : 1)
November 6, 2014 by Anonymous

chemistry
The half-life of C14 radioactive is 5760 yr. After how much time will 200 mg C14 sample be reduced to 25 mg?
May 3, 2015 by yashpal

Quick Math
I have a question: How would you solve this? a dozen dozen apples at half a dozen dimes a dozen? In this cause is dozen 12? And half a dozen dimes in 60 cents? So half a dozen dozen is 144/2 so thats 72 correct? yes, half a dozen dozen is 144/2 = 72 but I don't know what that ...
December 5, 2006 by Gina

Chemistry
How much time in years (assume a 365 day yr) would it take for a 1.6678g sample of 239Np to decay to a mass of 0.8671g if it has a half life of 2.030*10^5s
May 6, 2011 by Jay

Ethics
Which of the following answers to the meaning of life did Tolstoy hold prior to his change of heart and mind? my answer is A a. Life has no meaning, and we must embrace that fact. b. Life's meaning is to provide comfort for oneself and one's family. c. Life's meaning is to ...
February 17, 2014 by Annmarie

Ethics
Which of the following answers to the meaning of life did Tolstoy hold prior to his change of heart and mind? my answer is A a. Life has no meaning, and we must embrace that fact. b. Life's meaning is to provide comfort for oneself and one's family. c. Life's meaning is to ...
February 17, 2014 by Annmarie

Physics help
how would you investigate if the half life of water dripping from a burette is constant? I know the method but what equation and principle would ya'll use?
February 17, 2008 by Daggeron

Chemistry
HCO2H(g) CO2(g) + H2(g) The half-life for the reaction at 550 C is 24 seconds. How many seconds does it take for the formic acid concentration to decrease by 75%?
November 11, 2009 by Anonymous

chemistry
What is the half-life of a compound if 69 percent of a given sample of the compound decomposes in 59 min? Assume first-order kinetics.
January 31, 2010 by danielle

chemistry
For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?
February 28, 2010 by joe

chemistry
For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?
February 28, 2010 by joe

chemistry
For the reaction A to products}, the following data were obtained: t=0 s, A}]=0.715 M; 22 s, 0.605 M; 74 s, 0.345 M; 132 s, 0.055 M. What is the half-life of the reaction?
February 28, 2010 by joe

Chemistry
half life of tritium is 12.5 years. how much will remain after 100 years if you started wit 256 grams?
October 14, 2010 by Anonymous

chemistry
the half-life of radon-222 is 3.823 days. what was the original mass if 0.050g remains after 7.646 days?
October 21, 2010 by Anonymous

chemistry
Iodine-131 has a half-life of 8 days. How many grams of a 12 g sample will remain at the end of 40 days? how do i solve this? i thought it was 12^40=1.5 but thats wrong...
November 18, 2010 by jess

Calculus
suppose that a population is dying with a half life of of 43years. The initial size is 1600. Find the 1 year DTDS for this population
February 6, 2011 by Anonymous

physics
if you have an element that starts out at 40g and has a half-life of 10 days, you keep it for 30 days- how much doe you end up with? .
April 7, 2011 by sandy

College Math
Only 43% ofthe carbon-14 in an artifact remains. How old is the artifact? Would the answer be less than the half life?
February 19, 2012 by Angel

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?
March 21, 2012 by Anonymous

Algebra 2
half life carbon -14 is 5,730 years. If you start out 50 grams, how long will it take until it reaches 2 grams?
May 20, 2012 by chels

Science
A certain isotope has a half-life of 12 hrs. How long will it take for 100 gr to decay into only 25 gr?
July 15, 2012 by Haley

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?
August 23, 2012 by aileen

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?
August 23, 2012 by aileen

Calculus
The half-life of Radium-226 is 1590 years. If a sample contains 100 mg, how many mg will remain after 4000 years?
November 16, 2012 by Anonymous

Math
assume the substance has a half-life of 11 years and the initial amount is 126 grams. How much remains at the end of 8 years?
January 25, 2013 by Jackie

chemistry
If something originally contained 32.0 g of Po-210, which has a half-life of 10.5 minutes, and was now 73.5 minutes old, how many grams would be left?
May 13, 2013 by Mary

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?
February 17, 2016 by Maria

science
Please help me with this question.... The isotope caesium-137, which has a half-life of 30 years, is a product of nuclear power plants. How long will it take for the amount of this isotope in a sample of caesium to decay to one-sixteenth of its original amount? k = 0.693/t1/2...
February 5, 2007 by Mary

English III
In Lucinda Matlock, what is the title character's attitude toward life? A. She thinks life is hard. B. She thinks life is worthwhile. C. She thinks life is boring. This one has to be C because she is happy all the time.
June 10, 2012 by Anonymous

math
an extremely volatile substance, Ofnetite, has a half-life of 25 minutes. Find the percentage decrease of this substance in the first two hours.
November 8, 2009 by katy

Chemistry 212
the half life of F18 is 2.089x10^-4yrs. How long would it take (in days) for F18 to decrease to 78.71% of its initial amount?
May 10, 2010 by pookie

Chemistry-help please!
The half-life of Xe-133 is 126 hours. Starting with 250. mg, after 500 hours around how many mg remain? A. 63 B. 16 C. 32 D. 125
May 23, 2010 by Charleze

math
Radioactive radium has a half-life of approximately 1599 years. What percent of a given amount remains after 100 years?
February 24, 2011 by rachel

math
Radioactive radium has a half-life of approximately 1599 years. What percent of a given amount remains after 100 years?
February 24, 2011 by rachel

chemistry
caffeine has a half-life of 4.6 hours in the human body.. How long would it take 125 milligrams tritium to decay to 22 milligrams?
April 11, 2011 by cam

Chemistry
carbon 14 has a half life of 5715 years. If you start with a 5 gram sample of 14C, what mass is left after 15,000 years?
April 24, 2012 by Mima

Chemistry
A fossil is found to have a C-14 level of 86% compared to living organisms. How old is the fossil?, (the half life of C14 is 5730 years).
April 27, 2012 by Mima

Chemistry
Carbon-14 has a half-life of 5730 years In a plant fossil you find that the 14 C has decayed to 1/8 of the original amount how long ago was this plant
September 24, 2012 by Shay

Science chemistry
It takes 1 hour and 17 min. for a 1.000gsample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp
September 24, 2012 by Shay

chemistry
It takes 1 hour and 17 min. for a 1.000g sample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp
September 24, 2012 by Shay

earth science
if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days
November 29, 2012 by lan

earth science
if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days
November 29, 2012 by lan

earth science
if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days
November 29, 2012 by lan

chemistry
Carbon-14 has a half-life of 5730 . In a plant fossil, you find that the has decayed to 1/32.0 of the original amount. How long ago was this plant alive?
December 3, 2012 by niles28

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?
December 5, 2012 by Owen

Biology
The half-life of Carbon-14 is 5730 years. What is the age of a fossil containing 1/16 the amount of Carbon-14 of living organisms? Explain your calculation.
December 9, 2012 by Melissa

UIW
Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239Np to decay to 0.100% of its original quantity
September 19, 2013 by Anonymous

Math
Suppose you have a cache of radium, which has a half-life of approximately 1590 years. How long would you have to wait for 1/5 of it to disappear?
March 26, 2015 by Will

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
October 12, 2010 by jay 1

College Chemistry
How much time in years (assume a 365 day yr) would it take for a 1.6678g sample of 239Np to decay to a mass of 0.8671g if it has a half life of 2.030*10^5s
May 5, 2011 by Jude

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?
December 10, 2011 by Jennifer

English
Especially when the game is called life. There can be a champion in each of us, If we live as a winner, If we live as a member of the team, If we live with a hopeful spirit, For life. ----------------------------- This is a poem. What is the meaning of the last expression "...
December 11, 2014 by rfvv

Life of a Soldier
Could you please give me some points, details explaining life of an average canadain soldier. Ive jotted down a few, but if you could give me some more, that would help me loads. Didn't get many hours of sleep Poor Living Conditions Had to stand out in the trenches daily, had ...
October 12, 2011 by Anonymous

chemistry 2
A voltaic cell is constructed with an Ag/Ag+ half-cell and a Pb/Pb2+ half-cell. Measurement shows that thesilver electrode is positive. -Write balanced half-reactions and the overall spontaneous reaction.
April 27, 2012 by anonymous

physics
A baseball leaves a pitcher's hand horizontally at a speed of 115 km/h. The distance to the batter is 18.3 m. (Ignore the effect of air resistance.) (a) How long does the ball take to travel the first half of that distance? (b) The second half? (c) How far does the ball fall ...
October 7, 2012 by tatiana

physics
A baseball leaves a pitcher's hand horizontally at a speed of 115 km/h. The distance to the batter is 18.3 m. (Ignore the effect of air resistance.) (a) How long does the ball take to travel the first half of that distance? (b) The second half? (c) How far does the ball fall ...
September 19, 2013 by kristy

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?
November 17, 2007 by Judy

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?
March 30, 2009 by mike

Science
If a radioactive isotope has half life of 5 days,how long will it take for its radioactive strength to be a maximum of one thousandth,(1/1000) of its original value?
December 21, 2010 by Bree

math
how to compute this problem? a certain element has a half life of 12 years. if there were 1000 milligrams originally, find the remaining amount after 20 years?
January 12, 2011 by diane

chemistry
the mass of cobalt-60 in a sample is found to have decreased from 0.800g to 0.200g in a period of 10.5 years. from this info calculate the half-life of cobalt-60
April 6, 2011 by shaleena

chemistry
the mass of cobalt-60 in a sample is found to have decreased from 0.800g to 0.200g in a period of 10.5 years. from this info calculate the half-life of cobalt-60
April 6, 2011 by shaleena

chemistry
a sample of a radioisotope had a mass of 100.0 grams. After exactly 24 days, 6.25 grams remained. The half life of the isotope is _________
June 3, 2011 by rick

chem
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. (a) How many beta particles are emitted in 47.0 s by a 2.39-mg sample of 60Co? i got 2.44e19 but thast wrong
September 12, 2012 by sara

math
3. The half-life of a certain drug in the human body is 8 hours how long it would take for a dose of this drug to decay to 0.1% of its initial level?
November 12, 2013 by hannah

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.
September 4, 2014 by lucy

chemistry
the half-life of the reaction, at 34 degrees celsius and Ppan=13.2 torr, is 164.0hr. Calculate the rate constant for the reaction. confused on what to do here
February 10, 2015 by mar

Physic
A newly prepared radioisotope has activity 3.7x10^11 Bq. After 4 hours, its activity is reduced to 2.96x10^11.calculate a) decay constant b) its half life
April 14, 2015 by Aboi

Physic
A newly prepared radioisotope has activity 3.7x10^11 Bq. After 4 hours, its activity is reduced to 2.96x10^11.calculate a) decay constant b) its half life
April 14, 2015 by Aboi

Physic
A newly prepared radioisotope has activity 3.7x10^11 Bq. After 4 hours, its activity is reduced to 2.96x10^11.calculate a) decay constant b) its half life
April 16, 2015 by Aboi

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?
April 27, 2015 by Molly

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?
July 30, 2015 by Jo

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.
December 1, 2015 by Sammantha Avants

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