Sunday

February 1, 2015

February 1, 2015

Number of results: 912

**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*

**geology / science**

the age of granite can be determind using radiometric dating, explain the basis for the determination of a 238 U- Pb radiometric date of 1120 Ma for a granite. I have as the answer 238 U decays to Pb with an experimental law, that is the amount of U and Pb in granite are ...
*April 18, 2007 by bex*

**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*

**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*

**Chemistry please check**

1. All of the naturally occurring radioactive decay series end when the radioactive elements have decayed to bismuth (Bi) hydrogen (H) lead (Pb) uranium (U) answer: Uranium (U) 2. This type of radiation can easily pass through a human. gamma ultra-violet beta alpha answer: ...
*February 15, 2008 by Mary*

**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*

**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*

**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*

**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*

**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*

**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*

**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*

**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*

**chemistry**

Radioactive decay is a process that follows first-order kinetics. The half-life of 32P is 0.03920 years; how long (in minutes) would it take for the amount of 32P to decrease to 53.25% of its initial amount? I don't understand at all what to do here
*May 11, 2014 by sara*

**Science**

Which of the following units are in order from smallest to largest? a) Epoch, period, era. b) Era, epoch, period. c) Period, era, epoch. d) Epoch, era, period. True or False? Folding, as well as motion along faults, can change the position of rock layers and how they line up ...
*September 23, 2014 by Sarah*

**Math+Growth/Decay**

3e^2x = G -3e^2x = G -3e^-2x = D 1/8e^2x = G -1/8e^-2x = D Would that be correct? I just made these examples up in my head. How can you tell if its growth or decay? I just look at the exponents. If is a negative then its decay? if its positive then its growth?
*March 11, 2009 by Chopsticks*

**Physics**

Is a small or large decay constant best for protection against gamma radiation? Hint: Calculate half thickness. Example: Decay constants for Pb, Al, water, and Fe are 0.77, 0.16, 107, and 0.44. Which is better for radiation shielding? The larger the decay constant, the fewer ...
*April 30, 2007 by Caleb*

**chemistry**

a radioactive material is undergoin nuclear decay. After 40 minutes, 25% of the sample remains. What is the half life of the sample? Pls say the formula how to calculate it a)10 mins b) 20 mins c) 40 mins d)80 mins e) 160 mins
*May 28, 2012 by star*

**Calculus-derivatives**

Verify if these are correct answers. 1. The derivative of f(x)=e^2x -e^-2x is f'(x)=2e^2x - 2e^-2x? 2.A certain radioactive substance is decaying so that at time t, measured in years, the amount of the substance, in grams, given by the function f(x)=3e^-3t. What is the rate of...
*March 6, 2012 by Matthew*

**Science**

Natural Uranium contains 15 percent Sm147. Sm147 is radioactive and decays by alpha decay. What will be the number of disintegrations per gram per second of the natural element? The half-life of Sm147 is 1.3x1010 years.
*September 30, 2012 by Nivia*

**science**

Predicting Table of radioactive isotopes below Isotope type of decay Uranium-238 Alpha Nickel-63 Beta Iodine-131 Beta Radium-226 Alpha With the help of a periodic table, predict the element that forms in each case. Explain your reasoning.
*May 4, 2014 by Andrean*

**chemistry**

If there are 80 milligrams of a radioactive element decays to 10 milligrams in 30 minutes then what is the elements half life in minutes? Ok i narrowed it down to either 10 or 30...but im rly confused so if u could help it wuld be grea 80 40 1 min 20 2 min 10 3min looks like ...
*March 4, 2007 by jojo*

**calculus**

A sample of a radioactive substance decayed to 94.5% of its original amount after a year. (Round your answers to two decimal places.) (a) What is the half-life of the substance? (b) How long would it take the sample to decay to 65% of its original amount?
*November 9, 2012 by kela*

**chemistry**

the longest lived radioactive isotope yet discovered is the beta-emitter tellurium-130.it has been determinded that it would take 2.4 x 10^21 years for 99.9% of this isotope to decay. write the equation for this reaction, and identify the isotope into which tellurium-130 decays.
*July 12, 2010 by penelope*

**Pre Calc**

The half-Life of radioactive earthium is 2651 years. Find how many years it will take 100 grams of earthium to decay to 10 grams. I know the equation is A=Ae^(-rt) I tried working it out but I think I am doing it wrong. I did 10=100e^(-r*2651) Can anyone help? Thanks a lot
*January 13, 2011 by Alex*

**ChemB**

measurements of carbon 14 taken from linen wrappings of the book of isaiah from the dead sea scrolls indicate that the scrolls contain 79.5% of the carbon 14 expected in living tissue. how old are these scrolls if the half life of carbon 14 is 5730 years? All radioactive decay...
*January 22, 2012 by L.Bianchessi*

**Science**

When Marie Curie Isolated uranium from pitchable, she realized that the [itchable was more radioactive than the uranium she had extracted. What did she conclude about her observations? pitchblende itself is a radioactive element the pitchblende sample contained an unknown ...
*January 7, 2015 by jeje*

**Chemistry**

Write a nuclear equation for the following: Iodine 131 undergoes beta decay two times Plutonium 239 is an alpha emitter Th 234 undergoes beta decay once and then alpha decay How do I go about writing nuclear equations?
*December 6, 2010 by Jake*

**Algebra**

Two different radioactive isotopes decay to 10% of their respective original amounts. Isotope A does this is 33 days, while isotope B does this in 43 days. What is the approximate difference in the half-lives of the isotopes? 3 days 10 days 13 days 33 days
*July 14, 2014 by Junior*

**Linear Algebra**

whats the exponential decay equation for 100 atoms that decay 1/20 per day
*January 12, 2012 by Anonymous*

**MATH help**

a certain radioactive isotope has a half life of approx 1,300 years . How many years to the nearest year would be required for a given amount of this isotope to decay to 55% of that amount. So I am not sure where to put the 1,300 1,300=2600*e^t or A=x*e^1300
*September 26, 2011 by HM*

**MATH help**

a certain radioactive isotope has a half life of approx 1,300 years . How many years to the nearest year would be required for a given amount of this isotope to decay to 55% of that amount. So I am not sure where to put the 1,300 1,300=2600*e^t or A=x*e^1300
*September 26, 2011 by HM*

**Math**

a certain radioactive isotope has a half life of approx 1,300 years . How many years to the nearest year would be required for a given amount of this isotope to decay to 55% of that amount. So I am not sure where to put the 1,300 1,300=2600*e^t or A=x*e^1300
*September 27, 2011 by HM*

**MATH help**

a certain radioactive isotope has a half life of approx 1,300 years . How many years to the nearest year would be required for a given amount of this isotope to decay to 55% of that amount. So I am not sure where to put the 1,300 1,300=2600*e^t or A=x*e^1300
*September 27, 2011 by HM*

**chem**

Nuclide X has decay constant 1.08 h-1. It can decay in 2 branches, to nuclide Y or to nuclide Z: X --> Y, with decay constant 0.43 h-1, and X --> Z, with unknown decay constant. If there are 10 moles of nuclide X at time t = 0, how many moles of each daughter will there ...
*October 21, 2013 by Jane*

**physics**

A building has become accidentally contaminated with radioactivity. THe longest lived material in the building is strontium-90 (atomic mass of 90 Sr 38 is 89.9077). If the building initially contained 5.0kg of this subtstance and the safe level is less than 10.0 counts/min, ...
*February 16, 2007 by soojung*

**Geology**

How do I do the foll9owing example? K-40 - A-40 (1.25 billion years) After careful analysis, a geochronologist determines that an unweathered, unmetamorphosed mineral sample contains 7 trillion atoms of the radioactive element K-40 and 105 trillion atoms of its decay product A...
*October 25, 2012 by Nicole*

**Calculus**

A fragment of bone is discovered to contain 20% of the usual carbon-14 concentration. Estimate the age of the bone to the nearest hundred years, given that Carbon-1 is radioactive with half-life of 5730 years and the rate of decay is given by the following differential ...
*May 21, 2014 by Kristin*

**Math with science**

Radioactive iodine treatment is so successful at treating hyperthyroidism that it has virtually replaced thyroid surgery. To the nearest full day, determine how long it will take for 400 millicuries of I-131, which has a half-life of 8 days, to decay to 3.125 millicuries. 56 ...
*July 27, 2008 by Liz*

**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*

**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*

**College Physics II**

A typical gamma ray emitted from a nucleus during radioactive decay may have an energy of 736 keV. What is its wavelength? A microwave oven produces electromagnetic radiation at λ = 12.1 cm and produces a power of 778 W. Calculate the number of microwave photons produced ...
*November 25, 2010 by VJC*

**Calc**

A sample of a radioactive substance decayed to 93.5% of its original amount after a year. a) What is the half-life of the substance? ? years (b) How long would it take the sample to decay to 10% of its original amount? ? years
*November 8, 2009 by Lee*

**Algebra please check my answers**

1) The linear function f(x) contains the points (-10, -29) and (-2, 83). If g(x) = 25x - 50, which statement is true? A. The functions f(x) and g(x) both have positive slopes. <<< B. The functions f(x) and g(x) both have negative slopes. C. The function f(x) has a ...
*May 21, 2014 by David*

**Algebra 2 Decay **

You have 20 grams of phosphorus-32 that decays 5% per day. How long will it take for hlaf of the original amount to decay?
*February 17, 2012 by Peter*

**Biology**

Help please! Do organic fertilizer products (in bags or sacks) decay after some time? If yes, how long will it take to decay?
*March 8, 2012 by Namie*

**chemistry**

The question I am having trouble with is: Scientists originally were uncertain whether the oxygen gas produced during photosynthesis came from CO2, H2O, or from both. How could radioisotope tracers be used to settle that question? Chemistry - DrBob222 6CO2 + 6H2O ==> ...
*April 15, 2013 by Madison*

**Calculus**

The half life of a certain radioactive substance is 10 years. How long will it take for 18 gms of the substance to decay to 6 gms? A. 6 ln 10 years B. 10 ln 6 years C. 10 (ln 3)/(ln 6) years D. 18 ln 10 years E. 10 (ln 3)/(ln 2) years
*January 27, 2013 by Anonymous*

**PHYS**

Help! Initially there are 6x10^9 radioactive of element W (decay constant 0.173/day) in a sample. As a nucleus of W decays, it converts 2.67x10^-28 kg of its mass to energy and releases the energy. How much time (in days) is required for the sample to releae a total of 7.2x10...
*April 25, 2011 by Jenn*

**pre calculus **

The age of a document is in dispute, so archaeologists test for carbon-14. Due to radioactive decay, the amount A of carbon -14 present compared to the initial amount A0 after t years is given by the formula A(t) = A0e^-0.000124t . If 72% of the original amount of carbon- 14 ...
*February 8, 2014 by Raju*

**Science**

Under which of the following conditions would a fossil most likely form? a. a living thing dies and sediment is very slowly deposited on top of its body b. a living thing dies and sediment quickly covers its body* c. a living thing dies and its skeleton is left exposed to the ...
*October 30, 2013 by Anonymous*

**CHEMISTRY**

Suppose you had a detection device that could count every decay event from a radioactive sample of plutonium-239.052156 (t1/2 is 24,000 yr). How many counts per second would you obtain from a sample containing 0.126 g of plutonium-239? (The mass of Pu-239 is 239.052156 u. ...
*September 5, 2012 by Maryanne*

**Algebra I**

A sample of radioactive material weighing 45 grams has a decay rate of 4.25% each day. The equation y = 45(2.7)–0.0425t can be used to find the amount of material that still remains, where t is the number of days that have passed. Approximately what is the amount of material ...
*March 22, 2011 by Sarah*

**Chemistry**

The age of a rock can be estimated by measuring the amount of 40Ar trapped inside. The calculation is based on the fact that 40K decays to 40Ar by a first-order process. It also assumes that none of the 40Ar produced by the reaction has escaped from the rock since it was ...
*May 21, 2009 by Matt*

**Science-3 questions.**

Which of the following best describes the climates of Europe and North America during the 1.8 million years of the Quaternary period? hot and dry cool and rainy periods followed by droughts warm and mild a series of ice ages followed by periods when the glaciers melted Which ...
*December 11, 2013 by Princess Anna*

**science - biology**

A photosynthesis experiment uses Chlorella to track the route taken by 14C in photosynthesis. The 14C is provided from CO2 and no new sources of CO2 are available. After the experiment the scientist extracts all of the starch produced and analyses the Carbon present. She ...
*May 7, 2011 by jack*

**biology**

14 points Save A photosynthesis experiment uses Chlorella to track the route taken by 14C in photosynthesis. The 14C is provided from CO2 and no new sources of CO2 are available. After the experiment the scientist extracts all of the starch produced and analyses the Carbon ...
*May 7, 2011 by jack*

**chemistry**

if you start with 100mg of radioactive material that has a half life of one hour, how many mg's of radioactive material would you have in 10.2284952 hours?
*February 1, 2011 by carlos*

**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? Can anyone give me a VERY SIMPLE explanation of this please? Thank you.
*January 29, 2011 by Korina*

**Chemistry**

If a 100.0 gram sample of a radioactive isotope goes through three half-lives, how much of the original radioactive isotope will remain?
*January 24, 2013 by OhSnap*

**Concentration and Reaction**

The rate of the following reaction: Radioactive decay of 90Sr, is characterized by the rate constant k = 0.024 year-1. What is the half-life (in years) for this reaction at the same conditions when the initial concentrations are 0.0356 M? (Round your answer to 3 significant ...
*November 20, 2010 by Confused*

**Chemistry**

It takes about 10^16 years for just half the samarium-149 in nature to decay by alpha-particle emission. Write the decay equation, and find the isotope that is produced by the reaction.
*July 14, 2010 by Phillip*

**Exponential Decay**

the half-life of carbon-11 is 20 minutes. How long will it btake for 600g of carbon-11 to decay to 30g?
*October 22, 2009 by Mark*

**physics**

Although most natural potassium nuclei are stable 39K (93.3%) or 41K (6.7%) nuclei, about 0.0117% are radioactive 40K nuclei, which have a half-life of 1.26 billion years. If you were worried about 40K radioactivity and wanted to wait for 97 % of the 40K in the environment to ...
*June 6, 2013 by Anonymous*

**chemistry**

can you tell me how the beta-plus decay process may be understood (i) at the level of individual nucleons and (ii) at the level of quarks, by writing a decay reaction in each case.
*May 2, 2009 by mathew -b*

**Physics**

A first order exponential decay can be written as A(t)= Ae^(-t/r) where A(t) is the amount (of substance) after time t, A is the initial amount at time t=0 and r is the decay time. The fall time is defined as the time in which A(t) falls from 90% to 10% of its initial value. ...
*October 11, 2008 by Beth*

**chemistry (urgent)**

can you tell me how the beta-plus decay process may be understood (i) at the level of individual nucleons and (ii) at the level of quarks, by writing a decay reaction in each case.
*May 2, 2009 by mathew -b*

**Math**

Classify the model as exponential growth or exponential decay. Identify the growht or decay factor and the percent increase or decrease per time period.
*November 4, 2010 by Nikki*

**CHEMISTRY HELP !!!! **

Which of the following statements is/are CORRECT? 1. Naturally occurring isotopes account for only a small fraction of known radioactive isotopes. 2. A few radioactive isotopes with long half-lives, such as U-235 and U-238, are found in nature. 3. Trace quantities of some ...
*May 6, 2014 by Kimberly :(*

**science**

Does anybody know any real life example of a nucleus Are you speaking of nucleus as in the nucleus of an atom or the nucleus of a living organism? If the former, the nuclear atom bomb or H bomb or the decay of radioactive materials to bombard some cancer patients to kill the ...
*April 15, 2007 by Amy L.*

**p**

A uranium nucleus (mass 238 u), initially at rest, undergoes radioactive decay. After an alpha particle (mass 4.0 u) is emitted, the remaining nucleus is thorium (mass 234 u). If the alpha particle is moving at 0.052 the speed of light, what is the recoil speed of the thorium ...
*March 14, 2012 by opp*

**physics**

A uranium nucleus (mass 238 u), initially at rest, undergoes radioactive decay. After an alpha particle (mass 4.0 u) is emitted, the remaining nucleus is thorium (mass 234 u). If the alpha particle is moving at 0.055 the speed of light, what is the recoil speed of the thorium ...
*March 3, 2014 by jill*

**Chemistry**

The rate constants for a first order decay reaction are found to be: K287.3C = 1 X 10-4s-1 K327.4C = 19.2 X 10-4s-1 (a) Determine the value, in s-1 of K250C (b) How long will it take, at 350C, for the reactant to decay to 1% of its original concentration? Express your answer ...
*January 11, 2013 by Chemgam*

**chemistry**

which of the following is consistent with the line spectrum of the hydrogen atom? one of the choices is the nucleus is udnergoing gamma decay. but this si not one of the answers. Im just wondering what kind of decay happens?
*October 18, 2014 by sara*

**Science**

Look at the table of radioactive isotypes below. Isotype Type of Decay Uranium-238 Alpha Nickel-63 Beta Iodine-131 Beta Radium-226 Alpha With the help of a periodic table, predict the element that forms in each case. I'm confused by this. Am I suppose to research each of the ...
*May 19, 2014 by Ninan*

**Physics check**

Why does a hydrogen bomb produce significant radioactive fall-out? A hydrogen bomb operates with a nuclear reaction that produces radioactive products?
*April 25, 2008 by Emily*

**precal**

If the half-life of a certain radioactive substance is 2000 years, estimate how many years must elapse before only 35% of the radioactive substance remains?
*January 22, 2013 by james*

**Science**

What process involves the comparison of rock layers with others in a sequence to determine its age? radioactive decay radiometric dating relative dating absolute dating To determine the most accurate and precise age of Earth's oldest rocks, geologists would use relative dating...
*October 30, 2013 by Abby*

**math30**

The mass of a radioactive sample is represented in the graph below. The initial mass of 32 mg decays to 8 mg after 21 hours. 1)What is the half-life of the radioactive sample, in minutes? 2)Solve each equation. a. 4 8x-1 = 8 b. 3^(2x-5) = 1/27x
*July 3, 2012 by alejandro*

**maths**

Choose three options which are examples of exponential growth or decay. A) The number in the sequence 2,6,24,120,720…… B) The amount of money in a bank account which earns compound interest. C) The radioactivity of a sample of a radioactive isotope. D) The savings of a person ...
*April 19, 2007 by katie*

**math**

i have this question and im not sure how to do it i keep getting stuck with these types of questions and i would appreciate some help (a) The rate of decay of a radioactive substance, S, is proportional to the amount remaining, x. Given that x = a at time t = 0, show that, if ...
*December 16, 2009 by jemmy*

**Calculus Help Please!!! URGENT!!!!**

Carbon-14 has a half-life of 5700 years. In a living organism, the ratio of radioactive carbon-14 to ordinary carbon remains fairly constant during the lifetime of the organism. After the organism’s death no new carbon is integrated into the organism’s remains, so the ...
*April 7, 2014 by Taylor*

**Emergancy help!!!!!!!!! **

Classify the model as exponential growth or exponential decay. Identify the growth or decay factor and the percent increase or decrease per time period. y=16(1.25)^t
*November 4, 2010 by Nikki*

**chemistry**

One way in which atomic nuclear decay takes place?What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*August 30, 2011 by Boricua*

**Chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*March 30, 2010 by Marlene*

**Chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*March 30, 2010 by Marlene*

**chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*May 1, 2010 by JanetJ*

**chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*July 25, 2010 by Art*

**chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*June 18, 2011 by Jessica*

**physics again**

and if they are the same (refer to the question before by me - copper and copper 64 being the same thing?)is it a radioactive isotope? thanks That was part of my previous answer. Yes, Cu-64 is radioactive. You need a handbook or table of radionuclides to figure that out. It is...
*February 20, 2007 by naomi*

**Chemistry**

radioactive sodium chloride is appropriate for diagnosing circulatory problems, but radioactive xenon is helpful in searching for lung problems. Explain why. I understand different elements are used for specific parts of the body but I don't understand this question. Thanks ...
*April 14, 2013 by Sara*

**college chemistry**

Discuss in detail, one way in which atomic nuclear decay takes place. What is the significance of atomic nuclear decay? Analyze the societal implications of using this process.
*December 8, 2010 by jane*

**Chemistry**

Gallium65, a radioactive isotope of gallium, decays by first order-kinetics. The half-life of this isotope is 15.2 min. How long would it take for 7/8 of a sample of this isotope to decay? 15.2 min 30.4 min 45.6 min 48.0 min I'm not sure how to do this. I initially tried by ...
*March 28, 2010 by Val*

**Physics HELP HELP**

(for some reason I keep getting this wrong. I put 90 for c, 5.6 for h and 22 for M(x), Then I took the natural log of both sides, but I keep getting it wrong) The mass of a radioactive element at time x is given by the equation below, where c is the original mass and h is the ...
*November 10, 2010 by Anonymous*

**physics**

Radioactive decay of granite and other rocks in Earth's interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.03 J per kilogram each year.Find an increase in ...
*April 1, 2012 by christy*

**math**

write the exponential function y=40e^0.06t in the form y=ab^t. find b accurate to 4 decimal palces. if t is measured in years, give the % annual growth or decay rate and the continuous % growth or decay rate per year.
*June 27, 2012 by Ariel*

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