A sample has a half life of 100 years. If it has been 200 years since it started to decay and there is 300 g of the sample left, how many grams were initially present in the sample?

Q: 1. A substance has a mass of 5 grams after decaying for 100 minutes. What was the mass of the…

A: Given that: Mass of substance left after decaying = 5 g Total time for decaying of substance = 100…

Q: The half life of an isotope is 43 seconds.  How long does it take 100.00 g of that isotope to decay…

A: Given that  Initially weight of isotope sample = 100.0 gm initially number of atoms of isotope No=…

Q: Consider a radioactive sample with a half-life of one week. How much of the original sample will be…

A: Half-life period is defined as the time taken for amount of the sample to reduce to half of its…

Q: The half-life of strontium-90 is 28 years. H

A: Given t1/2 of a reaction is 28 years  decay constant  (λ) λ = 0.693t1/2     = 0.69328 y     =…

Q: 30% of a radioactive substance has decayed after 10years, what is its half-life?

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Q: If a rock contained 12.0 g of ⁴⁰K when the earth was formed 4.54 billion years ago and the half-life…

A: Given information is as follows; Initial mass of ⁴⁰K in the rock A0 = 12.0 g Final mass of ⁴⁰K in…

Q: A rock contains 0.257 mg of Pb-206 for every milligram of U-238.The half-life for the decay of U-238…

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Q: After 20 years, only 3.125% of the initial amount of radioactive isotope is left. What is the…

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Q: If you start with 71.0 grams of a radioactive substance with a half life of 3 days, how much will be…

A: Here given, Initial amount (N0) = 71 grams Half life (t1/2) = 3 days Time (t) = 15 days Amount left…

Q: A piece of literature has announced that Uranium 238( 23822U) has a binding energy of approximately…

A: We can theoretically calculate the mass of a neutron. But this will be different from the…

Q: 222Rn has a half-life of 3.82 days. If a sample contains 36.2 mg of 222Rn, what mass of the isotope…

A: We have to calculate the amount after 6.81 days.

Q: Barium -122 has a half life of 2 minutes. Suppose you obtain a sample weighing 10.0g and it takes 10…

A: Since the decay reactions are first order reactions. Hence the half life of reaction will remain…

Q: A radioactive isotope has a half-life of 11 minutes.  How many grams of a 18.68 g sample remain…

A: Given Half life = 11minutes = 11*60= 660 second Sample weight = 18.68g Time = 44 minutes = 44*60=…

Q: The half life of an isotope is 43 seconds.how long does it take 100.00 g of isotope to decay to 6.25…

A: Given data contains, Half-life of an isotope is 43 seconds. Mass of isotope before decay is 100.0 g.…

Q: Plutonium – 236 is an alpha emitter with a half-life of 2.86 years. If a sample initially contains…

A: Given data Half life : t1/2=2.86 year Initial amount : No=2.56 mg time : t=7 year…

Q: What is the half life of a radioactive sample , if 3/4 of its nuclei decay in 2 years ?

A: Given:The amount of nuclear decay in 2 years = ¾ th of initial massAssume that the initial mass =…

Q: After 60 days, 10 grams of radioactive isotope remains from an original 27 g sample. What is the…

A: Given,

Q: Cs-134 has a half-life of 2.0 years. How much of a 2.50-g sample of this isotope will remain after…

A: Given :- half life of Cs-134 = 2.0 years                Initial amount of sample = 2.50-g  To…

Q: After 119 days have elapsed, 1/12 of a radioisotope sample remains undecayed. What is the half-life…

A: Amount of radioisotopes remaining = 112 of the initial amount Number of days taken for the decay =…

Q: A radioactive isotope has a half-life of 12.0 seconds. How much of a 100 gram sample is left after…

A: Given  Initial Mass of Sample ( A)0  = 100 gram  Half life time ( t1/2)   = 12 sec  Time ( t ) = 36…

Q: How long will it take for a 40.0-gram sample of Iodine-131 to decay to 1/16th of its original mass?…

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Q: Potassium-40 decays to argon-40 with a half-life of 1.27 * 109 yr. What is the age of a rock in…

A: It is given that potassium-40 decays to Argon-40 and has a half-life of 1.27×109 years and the mass…

Q: An unknown radioactive element decays into non-radioactive substances.  In 660 days the…

A: Rate constant (k)= 2.303/t log 100/49 So k = (2.303/660) ×0.3098 =0.0011 days ^-1

Q: Carbon-14 has a half-life of 5,730 years. If a sample contained 70 mg originally, how much is left…

A: Carbon-14 has a half-life of 5,730 years. If a sample contained 70 mg originally, how much is left…

Q: An 80 g sample of radioisotope decayed to 10 g after 24 days. What was the total number of grams of…

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Q: Radium-226 is radioactive and has a half life of 1600. years. How long would it take a sample to…

A: The emission of energy in the form of the ionizing radiation is called radio decay.This radiation…

Q: 2. If a sample known to be about 17190 years old has 400 carbon-14 atoms, how many atoms were in the…

A: When organism died absorption of C-14 stops and starts diminishing. The radioactive decay follows…

Q: At a certain instant, 100 grams of radioactive substance is present. After 20 years, 99.76 grams…

A: The half-life is the time required to change the initial amount to half of the amount. It is denoted…

Q: Calculate the age of a fossil that had 100 g of C-14 and now it has 12.5 g of C-14. The half-life of…

A: Use first order kinetic formula to get answer. Half life is given in years so we can use first order…

Q: A certain radioactive material is known to decay at a rate proportional to the amount present. If…

A: Consider the given information is as follows; Initial amount N0 = 500 mg Amount after 3 Nt years =…

Q: The​ half-life of​ silicon-32 is 710 years. If 20 grams is present​ now, how much will be present…

A: Radioactive decay is always a first order reaction. The rate equation for the radioactive decay is :…

Q: At a given time, there are 1.2 mg of a radioactive substance present. After 6 hours there is only…

A: To solve this question, first find out the rate constant of radioactive substance and using that…

Q: After 19 days have elapsed, 1/21 of a radioisotope sample remains undecayed. What is the half-life…

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Q: 187 Cs has a half-life of 30.2 years. How many years will it take for a 100.0-g sample to decay to…

A: Half life means time takwen by the sample to reachhalf of its concentartion.  Remains afetr t time =…

Q: How much of a 0.230 g radioactive sample with a half-life of 8 hours would remain after a period of…

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Q: If a rock sample was found to contain 1.27 x 10-7 mol of argon-40, how much potassium-40 would also…

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Q: If 20% of the radioactive substance disappears in one year, find its half-life assuming exponential…

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Q: If a tree dies and the trunk remains undisturbed for 1.170 × 10' years, what percentage of the…

A: This is a first order reaction. t½ = 0.693 ÷ k 5730 = 0.693 ÷ k k = 1.21 × 10-4  year-1 where k is…

Q: What is the half-live of a radioactive isotope if it takes 6.2 days for a 72g sample to decay to…

A: Given, 72 g to decay to 18 g. t = 6.2 days To calculate the half-life.

Q: what is the half life of an isotope that decays to 25% of its original activity in 68.9 hours?

A: For a first order reaction, rate constant can be calculated as

Q: A rock contains a Pb-206 to U-238 mass ratio of 0.473:1.00. Assuming the rock did not contain any…

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Q: The half-life of a given radioactive substance is 2.5 minutes. What fraction of the original…

A: Given, half-life , t1/2 = 2.5 min                     and, t = 10 min We need to calculate the…

Q: A rock contains 0.257 mg of lead-206 for every milligram of uranium-238. The half-life for the decay…

A: The first-order rate law can be transformed into another highly useful equation with the decay…

Q: After 119 days have elapsed, 1/21 of a radioisotope sample remains undecayed. What is the half-life…

A: Suppose the initial amount of sample be Ao After 119 days, amount remaining, A = (1/21) Ao The…

Q: Iron-59 has a physical half-life of 45 days. If 96 g of a radioactive iron sample (59Fe) is received…

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Q: A 371.9 ng sample of an unknown radioactive substance was placed in storage and its mass measured…

A: On passing a half life the concentration of the substance becomes half. Let the substance has passed…

Writing and Balancing Nuclear Equations

A nuclear equation is a symbolic representation of a nuclear reaction using certain symbols. It is studied in nuclear chemistry and nuclear physics.