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 halflife of this material? (in days)
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A sample of an unknown material appears to weigh 295 N in air and 165 N when immersed in alcohol of specific gravity 0.700. (a) What is the volume of the material? ___________m^3 (b) What is the density of the material? ____________ kg/m3 I am getting the

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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

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The function A=A0e^0.01386x models the amount in pounds of a particular radioactive material stored in a concrete vault, where x is the number of years since the material was put into the vault. If 500 pounds of material are placed in the vault. A) How

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Suppose that you are given a 100 gram sample of a radioactive substance with a halflife of 32 days. How many grams will be left after 192 days?

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The amount A in grams of radioactive plutonium remaining in a 20gram 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?

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The halflife of a certain radioactive material is 38 days. An initial amount of the material has a mass of 497 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 4 days. Round your

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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 I131, which has a halflife of 8 days, to decay to

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The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass of the sample. Round your

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A 15g sample of radioactive iodine decays in such a way that the mass remaining after t days is given by m(t) = 15e^(−0.051t), where m(t) is measured in grams. After how many days is there only 3 g remaining?

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The halflife for the radioactive decay of calcium47 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?

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An unknown radioactive element decays into nonradioactive substances. In 120 days the radioactivity of a sample decreases by 59 percent. What is the half life of the element? How long will it take for a sample of 100 mg to decay to 77 mg? The answer is

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8. The halflife of a certain radioactive material is 71 hours. An initial amount of the material has a mass of 722 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 17 hours. Round

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A radiation lab orders 64uCi of P32. After 42 days the activity of the sample is 8.0uCi. What is the life of P32? Thanks

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A half life of a certain radioactive is 36 days. An initial amount of the material has a mass of 487 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 5 days. Round your answer to the

physicsRadioactivity
1) The number of radioactive nuclei in a particular sample decreases over a period of 15 days to oneseventeenth the original number. What is the halflife (in days) of these nuclei? 2) What is the activity of a sample of 14C that contains 1.22E+21 nuclei?

math
An unknown radioactive element decays into nonradioactive substances. In 100 days the radioactivity of a sample decreases by 64 percent. a)(a) What is the halflife of the element? halflife: b)How long will it take for a sample of 100 mg to decay to 51

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a sample of radioactive iodine (half life=3 days) originally weighed 10 g, but now weighs 0.625 g. How old is the sample?

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An unknown material has a normal melting/freezing point of 20.4 °C, and the liquid phase has a specific heat capacity of 179 J/(kg C°). Onetenth of a kilogram of the solid at 20.4 °C is put into a 0.130kg aluminum calorimeter cup that contains 0.198

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6. The halflife of a certain radioactive material is 32 days. An initial amount of the material has a mass of 361 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 5 days. Round your

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

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It took 109.8 years for a 300.0 mg sample of an unknown radioactive material to completely disintegrate. Calculate the mass of the element (in grams/mole) assuming that the disintegrations per second are constant over the lifetime of the sample, and the

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Iodine131 is a radioactive isotope. After 8.00 days, 50.2% of the sample remains. What is the half life of 131I?

Chemistry Numerical
The half life period of a radioactive element is 27.96 days. Calculate the time taken by a given sample to reduce to 1/8th of its initial activity

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A particular radioactive element has a half life of 10.0 days. How much is left after 30.0 days if the sample started with 345g?

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a sample of sodium24 with an activity of 12 mCi is used to study the rate of blood flow in the circulatory system. If sodium24 has a halflife of 15 h, what is the activity of the sodium after 2.5 days. please show work.

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A radioactive sample contains 3.25 1018 atoms of a nuclide that decays at a rate of 3.4 1013 disintegrations per 26 min. (a) What percentage of the nuclide will have decayed after 159 d? % (b) How many atoms of the nuclide will remain in the sample? atoms

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You have just isolated a new radioactive element. If you can determine its halflife, you will win the Nobel Prize in physics. You purify a sample of 2 grams. One of your colleagues steals half of it, and eight days later you find that 0.1 gram of the

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The halflife of polonium is 139 days, but your sample will not be useful to you after 95 % of the radioactive nuclei present on the day the sample arrives has disintegrated. For about how many days after the sample arrives will you be able to use the

Chemistry
A particular radioactive element has a half life of 10.0 days. How much is left after 30.0 days if the sample started with 345g?

physics
A sample of an unknown material appears to weigh 285 N in air and 165 N when immersed in alcohol of specific gravity 0.700. (a) What is the volume of the material? Answer is in m3 (b) What is the density of the material? Answer is in kg/m3

science
A Geiger counter is used to measure the activity of a sample of iodine131. Based on the data, what is the halflife of iodine131? A. 16 days B. 8 days C. 4 days D. 12 days

chemistry
A radioactive sample contains 2.45 g of an isotope with a halflife of 3.8 days. How much of the isotope in grams will remain after 11.4 days?

Radioactivity
Beryllium7 has a halflife of 53 D. A sample was observed for one minute and there were 26,880 decays. a.) what is the activity level of the sample? b.) what will the activity level of the sample be after 265 d? c.) after how many days will be activity

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A sample of an unknown material appears to weigh 275 N in air and 160 N when immersed in alcohol of specific gravity 0.700. What is the volume of the material? What is the density of the material?

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A human body required 0.01 m activity of radioactive substance after 24 hours .Half li of radioactive substance is 6 hours .Then injection of maximum activity of radioactive substance that can be injected is : a). 0.08 b). 0.04 c). 0.16 d). 0.32

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Q1. The blood volume in a cancer patient was measured by injecting 5.0 mL of Na2SO4(aq) labeled with 35S (t1/2 = 87.4 d). The activity of the sample was 300 µCi. After 22 min, 12.9 mL of blood was withdrawn from the man and the activity of that sample was

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The halflife of Th(227) is 18.72 days. It decays by alfa emission to Ra(223), an alfa emitter whose halflife is 11.43 days. A particular sample contains 10^6 [10E(+6)] atoms of Th(227) and no Ra(223) at time t=0. a) How many atoms of each type will be in

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When a radioactive isotope releases a beta particle, the atomic number of the new element is A. decreased by one. B. decreased by two. C. increased by one. D. increased by two.

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 halflife of this material? (in days)

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University students, studying the activity of a particular radioactive isotope which had a halflife of 12.0 hours. If the original activity of the sample was 448 kBq, what would the activity be 3.00 days later?

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The activity of a sample of a radioactive isotope is 1800Bq. If this isotope has a halflife of 16 days, what is the activity after 16 days?, 24 days?, and 60 days?

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

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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

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Suppose 32000 radioactive nuclei are in a sample. About how many remain after two days if the halflife is 22 hrs? What is the initial activity of the sample in decays per minute?

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You have a sample of a certain radioactive substance. After two days, thirty percent of the sample has decayed. What is the halflife of the material and how much will have decayed after a week?

pre calc
You have a sample of a certain radioactive substance. After two days, thirty percent of the sample has decayed. What is the halflife of the material and how much will have decayed after a week?

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

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A radioactive sample of 141Cs has a halflife of 32.5 days. In a sample that contains 8.00*10^7 nuclei of 141Cs, how many beta particles per second will be emitted? A 19.8 B 1.7*10^6 C 71 076 D 1185 E 2.47*10^7 The 141 supposed to be a superscript text,

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You have just isolated a new radioactive element. If you can determine its halflife, you will win the Nobel Prize in physic. You purify a sample of 2 grams.One of you colleges steals half of it, and 3 days later you find that 0.1 grams of the radioactive

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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?

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A sample of an unknown material appears to weigh 270 N in air and 165 N when immersed in alcohol of specific gravity 0.700. (a) What is the volume of the material? (b) What is the density of the material?

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The activity of a sample of Ba137m has decreased by 75% from its initial activity after 5.10 minutes. What is the halflife of Ba137m? What fraction of activity remains after 6.25 minutes? (A=Aoe (kt); k = .693/t1/2)

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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?

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A radioactive isotope(h=4.5days) was prepared. This isotope was used 14 days later when it had an activity of 6000000 Bq. What was the activity of this isotope when initially prepared?

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A 15g sample of radioactive iodine decays in such a way that the mass remaining after t days is given by m(t) = 15e−0.051t, where m(t) is measured in grams. After how many days is there only 1 g remaining?

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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 halflife of the radioactive sample, in minutes? 2)Solve each equation. a. 4 8x1 = 8 b. 3^(2x5) = 1/27x

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I am getting the wrong answer. Can you please check my work? My answer is off by a multiple of ten. A sample of an unknown material appears to weigh 295 N in air and 165 N when immersed in alcohol of specific gravity 0.700. (a) What is the volume of the

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I am getting the wrong answer. Can you please check my work? My answer is off by a multiple of ten. A sample of an unknown material appears to weigh 295 N in air and 165 N when immersed in alcohol of specific gravity 0.700. (a) What is the volume of the

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An unknown radioactive substance has a halflife of 124 years. How long will it take a 67 grams sample to degrade to 18 grams?

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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?

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if the ration of water drops to EDTA is 6.7 for the known sample and 10 for the unknown sample what is the concentration of the unknown sample? (The concentration of the known sample is 315 ppm) a. 150mg/L b. 210mg/L c. 280mg?L d. 320mg/L

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A certian radioactive isotope has a halflife 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?

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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 halflives of the material after which the waste is no longer considered radioactive.

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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.

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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

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The quantity Q of radioactive carbon remaining in a 200gram wood sample at time t is given by the expression Q(t)=200e^(−0.000225⋅t). How much radioactive carbon remains in the sample after 100500 years? I just plugged in 100500 as t and got 3.02375

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A 10g sample of radioactive substances is lift to decay for five halflives. How much of the radioactive substance remains?