# radioactive decay

1,170 results

**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**

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.

**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

**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?

**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?

**Physics Help Please! Decay Questions**

archaeologist digging at the site of an ancient settlement discover the remains of a wooden structure. carbon 14 dating of the wood from the structure finds a decay rate of 180 decays/min. Knowing that the decay rate for living wood is 600 decays/min and the decay constant for...

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...

**calculus**

The rate at which an amount of a radioactive substance decays is modeled by the differential equation dA/dt = kA, where A is the mass in grams, t is the time in years, and k is a constant. Answer the following. a) If a 100-gram sample of the radioactive substance decays to 95 ...

**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? .

**Algebra**

Determine if the equation y = 2^x represents exponential growth or decay I thought at first it was growth but now I think it might be decay because there is no "b" in a parentheses so do I assume b is less than 1 so it's decay? Please help

**Science**

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

**precalculus**

Twenty percent of a radioactive substance decays in ten years. By what percent does the substance decay each year?

**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? .

**Science- Earth and its History**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...

**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 ...

**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?

**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

**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

**pre calc**

A 50 gram sample of radioactive strontium will decay to 32 grams in 18 years. a. Find an equation that will model how much of our sample M will remain after t years.

**Forensics**

Strontium-90 is a radioactive waste product from nuclear reactors. It has a half life of 29 years. How many years would it take for a quantity of strontium-90 to decay 1/16 of its original mass?

**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...

**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: ...

**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?

**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?

**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?

**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?

**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.

**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

**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?

**Math**

Does the function represent exponential growth or exponential decay. Identify the growth or decay factor. y=9 x (1/2) I'm not sure how to make the chart to show the decay.

**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?

**calculus**

The rate of decay in the mass, M, of a radioactive substance is given by the differential equation dM dt equals negative 1 times k times M, where k is a positive constant. If the initial mass was 100g, then find the expression for the mass, M, at any time t.

**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?

**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.

**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: ?

**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?

**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

**Physics Help Please**

archaeologist digging at the site of an ancient settlement discover the remains of a wooden structure. carbon 14 dating of the wood from the structure finds a decay rate of 180 decays/min. Knowing that the decay rate for living wood is 600 decays/min and the decay constant for...

**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?

**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 ...

**Chemistry**

The age of wine can be determined by measuring the trace amount of radioactive tritium, 3H, present in a sample. Tritium is formed from hydrogen in water vapor in the upper atmosphere by cosmic bombardment, so all naturally ocurring water contains a small amount of this ...

**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 ...

**Physics**

A radioactive isotope of Bismuth undergoes Beta Decay with a half-life of 22 days. How long (in days) will it take the Activity (A) of the sample to decrease to one-ninth of its original value? Assume that the original activity is A0.

**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

**science**

What order is the radioactive decay of carbon-14, an unstable isotope of carbon? A. Third order B. Second order C. Zero order D. First order

**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...

**Physics Help Please**

Scientists at Oak Ridge National Laboratory confirmed the existence of element 104 by creating 3000 atoms of it. If radioactive decay caused the number of atoms to drop by half within 4.0 s, how many atoms were left after 12 s? Show work please! Thank you!

**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.

**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.

**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 ...

**chemistry**

Radioactive waste is difficult to dispose of due to the long time periods needed before the radiation effectively disappears. The US protocol is to store the waste for 10 half-lives of the material after which the waste is no longer considered radioactive. After this time, ...

**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?

**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.

**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

**math 115**

A city of population 2.0 million is expected to experience a 15% decrease in population every 10 years. a. What is the 10-year decay factor? What is the yearly decay factor? The yearly decay rate? b. Use part (a) to create an exponential population model g(t) that gives the ...

**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...

**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 ...

**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?

**College Algebra**

This exercise uses the radioactive decay model. A wooden artifact from an ancient tomb contains 80% of the carbon-14 that is present in living trees. How long ago was the artifact made? (The half-life of carbon-14 is 5730 years. Round your answer to the nearest whole number...

**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

**Linear Algebra**

whats the exponential decay equation for 100 atoms that decay 1/20 per day

**Algebra**

Determine whether each function is an example of exponential growth or decay. Then find the y-intercept. a) y = 2(4)^x growth or decay y-intercept: b) y = 3(.25)^x growth or decay y-intercept:

**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

**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

**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

**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

**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 ...

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. The relative age of a rock is A, its age ...

**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, ...

**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...

**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 ...

**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 ...

**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

**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?

**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 ...

**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

**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 ...

**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?

**Biology**

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

**Science**

Which of the following characteristics x-ray photon emission? (a)electron capture (b)beta-decay (c)positron emmision (d)gamma-decay

**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 ==> ...

**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

**Chemistry(please check my answer)**

When a radioactive isotope undergoes Beta Decay, which of the following will NOT occur? A. The mass number of the original nucleus changes. B. The atomic number of the original nucleus changes. C. The original nucleus approaches greater stability. D. Energy is released.***

**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...

**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 ...

**Science**

When Marie Curie isolated uranium from pitchblende, she realized that the pitchblende was more radioactive than the uranium she had extracted. What did she conclude about her observations? A. Pitchblende itself is a radioactive element. B. The pitchblende sample contained an ...

**Calculus**

a certain radioactive substance is decaying so that at time t, measured in years, the amount of the substance, in grams, is given by the function f(t)=3e^-3t. What is the rate of decay of the substance after half a year: I first found the derivative of f(t)=3e^-3t which is f'(...

**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 ...

**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. ...

**College algebra**

If 70% of a radioactive element remains radioactive after 400 million years , then what percent remains radioactive after 600 million years? What is the half-life of this element

**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...

**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 ...

**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 ...

**Chemistry - radioactivity**

Hello Dr.Bob, could you please help me with this problem: Which of the following nuclides are most likely to decay via beta decay? a)200 78 Pt b)192 78 Pt c)188 78 Pt d)196 78 Pt