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December 19, 2014

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Number of results: 563

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
June 3, 2011 by J. J.

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

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.
January 15, 2009 by Amy

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

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

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
December 5, 2013 by ellie

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...
December 19, 2012 by joey

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

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
September 17, 2010 by Ashley

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
September 18, 2010 by Ashley

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

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.
December 6, 2011 by Rock

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.
December 8, 2011 by Rock

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
April 13, 2010 by lala

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
September 17, 2010 by ashley

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!!
June 3, 2011 by J. J.

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?
May 12, 2013 by Taylor

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
March 11, 2008 by william

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?
February 10, 2010 by ashley

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?
February 10, 2010 by ashley

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?
December 5, 2012 by Molly

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?
October 20, 2014 by Shay

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.
October 10, 2008 by jules

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?
March 10, 2008 by Rachel

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?
May 5, 2009 by Anonymous

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
August 27, 2013 by Colby

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? .
November 15, 2007 by Will

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.
November 21, 2014 by Zak

Science
How much of a radioactive material with a half-life of 12,000 years is left after 36,000 years of decay?
April 17, 2009 by Angie

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?
February 10, 2012 by cp

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
September 4, 2014 by Adrianna

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?
December 15, 2014 by Jason

physics
The half life of a radioactive sample is 6.93 days.after how many days will only one -tenth of the sample be left behind?
August 1, 2012 by Mira

chemistry
if the amount of radioactive iodine-123 in a sample decreases from .400g to .100g in 26.2 hours, what is the half-life of iodine-123
April 18, 2013 by j

Algebra
What are some real-life examples of exponential decay? Please help me think of some ideas...except radioactive decay.
January 30, 2014 by Anonymous

chemistry
A radioactive sample contains 2.45 g of an isotope with a half-life of 3.8 days. How much of the isotope in grams will remain after 11.4 days?
March 14, 2014 by Jacques

math
If 18g of a radioactive substance are present initially and 5 yr later only 9g remains, how much of the substance will be present after 11yr?
December 3, 2014 by Ernie

math
39mg radioactive with 1/2 life is decay total in 2.5 years. How many mg it remain if half of the amount is decay in 2 years? Thank you!
June 18, 2010 by Marie

precalculus
Twenty percent of a radioactive substance decays in ten years. By what percent does the substance decay each year?
March 3, 2011 by katrina

Chemistry
If the amount of radioactive iodine-123 in a sample decreases from 0.8 g to 0.1 g in 36.2 hours, what is the half-life of iodine-123
April 17, 2011 by Sara

physics
if 5/6th of a radioactive sample decay in 70 years and 1/6th remain. how can you find the half life without knowing the decay constant can you help?
May 21, 2008 by ronny

chemistry
a certain radioactive nuclide has a half life of 5.00 hour. Calcuate the decay rate for 1.000 mole of this nuclide __________ decay s-1
July 12, 2012 by eric

College Algebra
The half-life of a radioactive material is about 34.6 years. How much of a 1-gram sample of the material is left after 30 years?
October 20, 2012 by Anonymous

Math/Calculus
After 5 days, a particular radioactive substance decays to 37% of its original amount. Find the half life of this substance. Is this right? Th= ln 2/ln(1/.37) x 5 days
October 17, 2011 by Christine

physics ASAP
Can someone give me an example of how to use this formula: 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? .
November 18, 2007 by Will

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 ...
April 17, 2007 by jules

Science
Radioactive carbon-14 dating has determined that a fossil is 5.7 x 10 to the third power years old. What is the total amount of the original Carbon-14 still present in the fossil?
March 24, 2010 by Gina

Calculus
The amount A in grams of radioactive plutonium remaining in a 20-gram sample after t days is given by the formula A=20*(1/2)^(t/140). At what rate is the plutonium decaying when t=2 days?
November 30, 2010 by Sara

calculus
How do I set-up/solve this problem? Please help me. The half-life of the radioactive isotope gallium-70 is 20 minutes. If the initial amount of gallium-70 is 25 milligrams, when will 10 milligrams be left?
February 17, 2011 by Melody

math
How do I set-up/solve this problem? Please help me. The half-life of the radioactive isotope gallium-70 is 20 minutes. If the initial amount of gallium-70 is 25 milligrams, when will 10 milligrams be left?
February 17, 2011 by Amy

Pre Calculus
Exponential growth and decay find the half life of a radioactive substance if 220 grams of the substance decays to 200 grams in 4 years?
October 25, 2011 by Josh

TO ANY SCIENCE HELPER
I honestly don't get how to use radioactive dating to determine the age of a sample. I need an example and what to do in order to get the answer. I need it to be step by step. Thank u so much :)
April 17, 2014 by Anonymous

chem
A typical dose of a radioactive sample is 27.0 mCi. How long does it take for the activity to reduce to 0.100 mCi? The half life of the sample is 211,000 y.
September 19, 2014 by bekah

mathematics
what is the equation for exponetial decay(radioactive decay) and how to use the half life in the equation
November 2, 2011 by anonymous

physic
In a serious accident, a nuclear power plant's reactor vessel cracks, and all of the cooling water drains out. Although nuclear fission stops, radioactive decay continues to heat
May 6, 2014 by joseph

Physics check
A certain radioactive isotope has a half-life of one hour. At noon, 100g of the material is present. How much of the original isotope will be present at 3:00 p.m.----1/8 6:00 p.m.-----1/16 10:00 p.m.-----1/32 Are these correct?
April 21, 2008 by Sara

chemistry
A radioactive sample contains 2.45g of an isotope wiht a half life of 3.8 days. How much of the isotope in grams remains after 11.4 days? please explain
November 26, 2011 by Monique

ap calculus
suppose that the amount in grams of a radioactive substance present at time t (in years) is given by A (t) = 160e-.70t. Find the rate of decay of the quantity present at the time when t = 4
December 2, 2012 by steve b

math
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 0.964 g. What is the half-life, in seconds, of oxygen-19?
March 17, 2013 by Matthew

Maths
A radioactive substance decays exponentially in such a way that after 50 years, 60% of the initial amount remains. Find an expression for the quantity remaining after t years.
June 15, 2014 by Rish

Chemistry
Each of the following nuclides is known to undergo radioactive decay by production of a beta particle, ^0_-1e. Write a balanced nuclear equation for each process. (Use 'e' for an electron, 'p' for a positron, and 'n' for a neutron. Omit states-of-matter from your answer.) a...
November 27, 2010 by Jane

Physics
University students, studying the activity of a particular radioactive isotope which had a half-life of 12.0 hours. If the original activity of the sample was 448 kBq, what would the activity be 3.00 days later?
May 16, 2010 by Anonymous

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,...
September 21, 2007 by Anonymous

music
I have chosen Radioactive for my musical dance routine with my friend. I love this website and Radioactive. So.. I need a bit of help. I'm sticking to the song no matter what and I need advice from music tutors. This is what I have so far: Song playing in the background via ...
June 7, 2014 by Emz

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...
April 9, 2007 by Keisha

Chemistry
The half-life for radioactive decay of 14C is 5730 years (it emits β-particles with energy of 0.16 MeV). An archaeological sample contained wood that had only 72% of the 14C found in living trees. What is its age?
April 8, 2010 by Zoa

elem math
can some help me with my daughters homework. what figure is part of a line and has two endpoints? does a door have angles like a right , smaller or lager then a right angle? Seth made a picture frame with 4 equal sides and a right angle at each corner, what word best describes...
February 19, 2008 by Mrs.Green

12th grade
The radioactive isotope of Carcon (^14C)has a half life of 5730. What is the decay constant of ^14C? If we start with a sample of 1000 carcon nuclei, how many will be left in 22920 years time?
April 8, 2010 by Moe

Pre-Cal
The radioactive isotope of Carcon (^14C)has a half life of 5730. What is the decay constant of ^14C? If we start with a sample of 1000 carcon nuclei, how many will be left in 22920 years time?
April 8, 2010 by Moe

AP Environmental Science (URGENT)
Strontium-90 is a radioactive waste product from nuclear reactors. It has a half-life of 29 years. How many years will it take for a quantity of strontium-90 to decay to 1/16 (one-sixteenth) of its original mass?
January 11, 2012 by Heather

chem
Radioactive substances decay by first-order kinetics. How many years would be required for a sample containing strontium-90 to decrease to 58.32% of its initial activity? The half-life of strontium-90 is 2.88e1 years.
February 22, 2014 by sara

Earth Science
Describe how Earth would be different today if. It contained no radioactive material. What would the consequences be for the Earth's interior layer?
September 30, 2009 by Breanna

Earth Science
Describe how Earth would be different today if it contained no radioactive material. What would the consequences be for the Earth’s interior layers?
December 2, 2010 by Jack

Chemistry
32P is a radioactive isotope with a half-life of 14.3 days. If you currently have 48.1 g of 32P, how much 32P was present 3.00 days ago?
June 10, 2012 by Anonymous

algebra
Julie has 250 grams of a radioactive substance. The substance decays every hour. How long will it take until she has 20 grams of the substance left?
September 9, 2013 by Sozy

Radioactivity or science
A radioactive isotope source has a mass of 120ug. If the isotope had a half life of 20s, what would be the mass if the isotope after 2 mins?
April 21, 2014 by Jannet

chem
a radioactive fission product of nuclear explosions and sccidents is often iodine 131 which becomes distributed in the atmosphere. this falls upon the ground and is absorbed by plants. explain how this radiation could eventually beome concentrated in the human body and cause ...
February 3, 2008 by Amanda

chemistry
a radioactive fission product of nuclear explosions and sccidents is often iodine 131 which becomes distributed in the atmosphere. this falls upon the ground and is absorbed by plants. explain how this radiation could eventually beome concentrated in the human body and cause ...
February 4, 2008 by Amanda

science
radioactive decay occurs when atoms a) lose mass b) join with atoms of another element c) break down to form atoms of another element d) are exposes to chemical weather
December 13, 2013 by victoria

Radioactivity
How are the terms "activity" and "becquerel" related? A radioactive isotope source has a mass of 120 g. If the isotope has a half life of 20 secs what would be the mass of the isotope in 2 mins?
April 16, 2014 by Anonymous

chemistry
Rates of chemical reactions usually depend on temperature and pressure. However, half-life of all radioactive elements is independent of both T and p. How can these decay rates be independent of T if we beleive in the Arrhenius equation?
July 27, 2010 by Jin

Chemistry
A 71 mg sample of a radioactive nuclide is administered to a patient to obtain an image of her thyroid. If the nuclide has a half-life of 12 hours, how much of the nuclide remains in the patient after 4.0 days?
October 5, 2010 by Mr.Chemistry

Elem. Ed.
Can someone please give me input on this question? Complete immunization is usually required of chldren: 1.who will be turning 2 years old. 2.before they can travel across state line. 3.at the time they enroll in childcare programs. This question is confusing because when ...
April 15, 2007 by Keisha

Chemistry
All isotopes of technetium are radioactive, but they have widely varying half-lives. If an 800.0 g sample of technetium-99 decays to 100.0 g of technetium-99 in 639,000 y, what is its half life
December 11, 2012 by Matthew

science
The thermal energy of volcanoes and natural hot springs comes from trace amounts of radioactive minerals in common rock in the Earth's interior. Why isn't the same kind of rock at the Earth's surface warm to the touch?
January 30, 2008 by Ashton

earth science
what would be the chart to use for carbon 14 whcih has a half life of 5730 years and a piece of wood which originally has 12 grams pf radioactive isotope; If the half lives occurred and now has 0.75 grams left?
November 29, 2012 by lan

Algebra
In 10 years, 25% of a radioactive substance decays. What is its half-life? A. 25 years B. 24 years C. 20 years D. 29 years
December 12, 2012 by Darwin12

Math
In 10 years, 25% of a radioactive substance decays. What is its half-life? A. 25 years B. 24 years C. 20 years D. 29 years
December 14, 2012 by Darwin12

chemistry
radioactive disintegration is 1st order reaction. calculate the age of ancient wood piece if it shows a c14 activity of 20% compared to present day wood. if the half change time for c14 is 5600 years
December 5, 2011 by pinky

college
a certain radioactive isotope has a half life or 850 years.how many years would it take for a given amount of this isotope to decay to 70% of that amount?
December 2, 2010 by Kiesha

physics
After 1.84 days, the activity of a sample of an unknown type radioactive material has decreased to 85.8% of the initial activity. What is the half-life of this material? (in days)
June 3, 2012 by andrew

chemistry
Cobalt-60 is radioactive isotope used to treat cancers. A gamma ray photon emitted by this isotope has an energy of 2.13 x 10—13 J. What is the wavelength of this gamma ray in SI unit?
April 7, 2011 by John

Physics
Consider a radioactive sample with a half-life of one week. How much of the original sample will be left at the end of the second week? The third week? The fourth week?
August 29, 2013 by Tracee

chemistry
The half-life for the radioactive decay of calcium-47 is 4.5 days.If a sample has an activity of 4.00uCi after 13.5 days, what was the initial activity of the sample?
September 26, 2012 by Shay

physis
Search: 2. Explain how radioactive decay has always warmed the Earth from the inside, and nuclear fusion has always warmed Earth from the outside.
January 26, 2014 by barbara

Physics
Suppose a hypothetical radioactive nucleus (Hy) has a half-life of 10 days. If we have 80 gms of the substance at the start of an experiment, how many gms of the substance will remain undecayed after 30 days
May 10, 2008 by Tim

Physic II
The decay constant of a radioactive nuclide is 9.5x10^-3 s^-1 . At given instant, the activity of a specimen of the nuclide is 80 mCi. The time interval required for the activity to decline to 40 mCi is closest to: ?
April 30, 2014 by huline3

Half-life
After two hours, 1/16 of the initial amount of a radioactive isotope remains undecayed. What is the half-life of the isotope?
November 18, 2013 by Andrea

Chemistry
The half-life of phosphorus-32 is 14.26 days. The decay constant is k=4.86×10−2/days. 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?
May 1, 2011 by Anonymous

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