If there is a radiation that has a half life of 10 days and we have it for 110 days, what will be the fraction of radiation left?

21,946 questions
1. CALC -- integrals!

Iodine-131 is used to treat hypo-thyroidism since it is preferentially absorbed by the thyroid and typically involves a total radiation dosage of 10,000,000 millirem. Iodine-131 has a half-life of eight days. 1. Set up the appropriate integral to represent

asked by anonymous on February 4, 2008

Iodine-131 is used to treat hypo-thyroidism since it is preferentially absorbed by the thyroid and typically involves a total radiation dosage of 10,000,000 millirem. Iodine-131 has a half-life of eight days. 1. Set up the appropriate integral to represent

asked by anonymous on February 5, 2008
3. Chemistry

If there is a radiation that has a half life of 10 days and we have it for 110 days, what will be the fraction of radiation left?

asked by Jennifer on November 6, 2011
4. chemistry

If there is a radiation that has a half life of 10 days and we have it for 110 days, what will be the fraction of radiation left?

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5. chemistry

Some radioactive nuclides have very short half-lives, for example, I-31 has a half-life of approximately 8 days. Pu-234, by comparison has a half-life of 24,000 years. Explain why both of these examples are dangerous, even though their half-lives are very

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6. physics

If the physical half-life of sulfur-35 is 87.1 days, and the biologic half-life in the testicle is 632 days, what is its effective half-life in this organ? I know i have to find the time and then the half-life. But im having trouble finding the time

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7. half-life

1. The half-life of a first-order reaction is 9.89 minutes. How many minutes will have elapsed after 27 half-lives? My answer is 267.03. 2. The half-life of a second-order reaction is 2.508 days. How many days will have elapsed after 8 half-lives? My

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8. Chemistry

When is an isotope considered stable? _(Select all that apply.)_ The isotope does not emit a form of radiation. The isotope’s half-life is longer than the average human life. The isotope emits some form of radiation. The isotope’s half-life is too long

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A radioactive isotope, used in the agricultural industry has a half life of 8 days. On application, the radiation is emitted is measured at 12500 counts per sec (cps). If the area that it is applied to cannot be used until the radiation strength is less

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10. Gen Chem

Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239-Np to decay to 1.00% of its original quantity? I got: close to 15 days. Is this right? I figured that about 1% of the original quantity would be roughly 6.5 Half

asked by Sarah H on March 28, 2008
11. chemistry

How do you find the half-life of an element? Please explain and show me how to do this. I know the answer is 14.3 days, but I don't know how to work it. thank you! the problem is: After 42 days, a 2.0-g sample of phosphous-32 contains only 0.25g of

asked by Ryan on December 13, 2007
12. chemistry

The disintegration of a radioisotope, such as I-131 to Xe-131, is another example of a first-order reaction. It has a half-life of 8.0 days. I-131 -> Xe-131 + e If you start with 1.40 g I-131, how many grams of I-131 will be left after the following days?

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13. physics

If half life of iodine 131 is 8 days, how much from 32g remain after 40 days (5 half lives).

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14. math

The half life of the radio active substance is the time require the half the substance to decay. the mount A ( in grams) of 100 gram sample of a radio active substance remaining after t half lives by A equals to 100 (0.5) t. suppose the substance has a

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15. college

. S-35 (t1/2 = 87.4 d) is used in cancer research. The biological half-life in the human body is 90 days. What is the effective half-life of S-35?

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16. college chem

S-35 (t1/2 = 87.4 d) is used in cancer research. The biological half-life in the human body is 90 days. What is the effective half-life of S-35?

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17. Math

1. Iodine-131 is used to find leaks in water pipes it has a half life of 8.14 days. If 36 days have passed and there is now 2.34g left. What is the initial amount? 2. Sr-85 is used in bone scans and has a half life of 64.9 days. If there is 23 percent of

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18. Physics

Gold-198 with a half life of 2.6 days is used to diagnose and treat liver disease. Write a half life decay equation that relates the mass of au-198 remaining to time in days. What percentage of a sample of Au-198 would reamin after 1 day, 1 week? Given the

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19. math

You have just isolated a new radioactive element. If you can determine its half-life, 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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20. 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

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21. Algebra

Andrew measures the amount of a very unstable substance to be 100 moles. The half-life of this substance is 3 days (after 3 days, half is gone). Write an exponential function that models this situation where y is the amount of substance and x is time in

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22. algebra

Andrew measures they amount of a very unstable substance to be 100 moles. the half life of this substance is 3 days(after 3 days, half is gone). write an exponential function that models this situation where Y is the amount of substance and X is time in

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23. 12th grade Math - word problems

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24. Biology

_____________provided significant sources of energy on early Earth, and were most likely involved in the origin of life. Options A) Volcanic activity, violent thunderstorms, and ultraviolent radiation B) Bombardment from meteorites, gamma radiation, and

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26. science

A Geiger counter is used to measure the activity of a sample of iodine-131. Based on the data, what is the half-life of iodine-131? A. 16 days B. 8 days C. 4 days D. 12 days

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27. chemistry

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28. Math

A radioactive material takes 60 days to cut its radiation in half. If it starts at 100%, when will it be at 5%?

asked by Anonymous on June 19, 2014
29. science

a radioisotope, Iodine-131, has a half life of 8.1 days. explain what this means. draw a particle diagram for a sample 12 particles of I-131 initially after 8.1 days and after16.2 days.

asked by mason on May 24, 2016
30. Chemistry. Half Life Problem. Help Plz

If the half-life of iodine-131 is 8 day, how much would remain undecayed after 8 day if we started with 38 grams? How much at 16 days? 24 days? 32 days?

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A radioisotope has a half-life of 4 days. How much of a 20-gram sample of this radioisotope remains at the end of each time period? 1) 4 days 2) 8 days

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32. physics

if you have an element that starts out at 40g and has a half-life of 10 days, you keep it for 30 days- how much doe you end up with? .

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33. Pre-Calc

A radioactive isotope has a half life of 8.1 days. If the sample starts with 25 grams, how much will there be after 90 days?

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34. chem

The half-life of is 30.0 days. What fraction of a sample of this isotope will remain after 16.2 days?

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35. chemistry

Ba-140 has a half life of 13.0 days. What fraction of a sample will remain after 39 days?

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36. CHEM

An isotope has a half life of 56 days. It now has 10,000DPM/ml. What will its activity be 100 days from now?

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37. chemistry

The half life of phosphorus -32 is 14.3 days. What percentage of an original samples radioactivity remains after 57.2 days?

asked by matt on May 7, 2012
38. 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?

39. earth science

if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days

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40. Math

The half-life of radon-222 is 3.8 days. How much of a 300 gram sample is left after 14.8 days?

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41. earth science

if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days

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42. earth science

if carbon 14 has a half life of 24 days how much would be left of 220 gram sample after 168 days

asked by lan on November 29, 2012
43. Algebra

The half-life of radon-222 is 3.8 days. How much of a 300 gram sample is left after 14.8 days?

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44. ALGEBRA

You have 480 grams of a radioactive kind of tin. If its half-life is 10 days, how much will be left after 30 days?

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45. Science

The half-life of randon-222 is 8 days. What was the original mass if 6 grams remains after 24 days?

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46. math

If, initially, there is 20 mg of gold-198 (198Au) (half-life = 2.696 days), how many days does it take for less than 1 mg to remain?

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47. Chemistry

A radioactive element has a half-life of 6.41 days. What percent of the original sample will be left after 15.0 days?

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48. science

The iodine-131 nuclide has a half-life of 8.0 days. If you originally have a 257 g sample, after 48 days how much will you have?

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49. Algebra 2

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?

50. Chem

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51. algebra

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52. physics

The half-life of Th(227) is 18.72 days. It decays by alfa emission to Ra(223), an alfa emitter whose half-life 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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53. Chemistry

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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54. Energy

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55. chemistry

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56. Chemistry

Uranium-238 has half life of 4.51 * 10^9 years Uranium-234 has half life of 2.48 * 10^5 years Thorium-230 has half life of 8.0 * 10^4 years Radium-226 has half life of 1.62 * 10^3 years Lead-210 has half life of 20.4 years. The rate constant for the decay

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57. Chemistry

The iodine-131 nuclide has a half-life of 8 days. If you originally have 625-g sample, how many grams will you have after 2 months(approximately 64 days)?

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?

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59. UIW

Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239Np to decay to 0.100% of its original quantity

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60. chemistry

Iodine-131 has a half-life of 8 days. How many grams of a 12 g sample will remain at the end of 40 days? how do i solve this? i thought it was 12^40=1.5 but that's wrong...

asked by jess on November 18, 2010
61. Math

You have just isolated a new radioactive element. If you can determine its half-life, 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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62. Science Half Lives

I am confused about how to claculate half lives. Can you explain. ( How much of a 400 gm sample od gold is left after 10.8 days if the half life is 2.7)

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63. algebra

Consider that the half-life of Polonium-210 is 140 days.What approximate daily percentage of decay does Polonium-210 demonstrate?% (Round to two decimals.)(Hint: use the Rule of 70 backwards by dividing by the half-life period instead of the rate.) What

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64. Physics 30

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65. math

iodine 131 has a half life of 8 days. If 5 mg are stored for a week, how much is left? How many days does it take before only 1 mg remains? An explanation for each step would be nice please. I want to learn how to do these problems for my upcoming exam.

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66. Chemistry

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67. Chemistry (Dr.Bob222)

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68. calc

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69. Science

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70. Chemistry

If a 300g sample of a substance has a half-life of 5 days, how much of the substance will decay after 22 days? A)293.4 g B)290.6 g C)285.8 g D)299.9 g

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71. chemistry

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72. Chemistry

Ba-140 has a half life of 13.0 days. What fraction of a sample of Ba-140 will remain after 39 days? A. 1/8th B. 1/16th C. 1/2th D. 1/4th

asked by Charleze on May 23, 2010
73. Chemistry

2. The half-life of a radioactive element is important when considering its application in medicine. For example, iodine-131 is often used in the imaging of the thyroid. The reason is that iodine is readily absorbed by the thyroid gland. Another reason is

asked by Mickey on September 28, 2014
74. chemistry

The half-life of I-131 is 8.00 days. If a medical treatment involves a dose of 400. mg of I-131, how much of the isotope remains after 48 days? 3.125 mg 6.25 mg 12.5 mg 25 mg

asked by Tamera on December 2, 2014
75. calculus

The half-life of Radium-223 is 11.43 days. If a sample has a mass of 400 mg, find the mass (in mg) that remains after 6 days

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76. calculus

The half-life of Radium-223 is 11.43 days. If a sample has a mass of 900 mg, find the mass (in mg) that remains after 5 days

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77. chemistry

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78. Science

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79. 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

asked by Christine on October 17, 2011
80. Chemistry

The half-life of 131I is 8.021 days. What fraction of a sample of 131I remains after 24.063 days? 1/2 1/4 1/8 1/16 Please help. Thank you

asked by Kiki on January 24, 2014
81. Math

I need help in algebra 1. I have 4 questions, I already answered 3 of them, but I need help with the other Andrew measures the amount of a very unstable substance to be 100 moles. The half-life of this substance is 3 days (after 3 days, half is gone). 1.

asked by Ayriel on February 8, 2016
82. math

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

asked by Rachel on May 18, 2013
83. chemisty

Chromium-51 is a radioisotope that is used to assess the lifetime of red blood cells The half-life of chromium-51 is 27.7 days. If you begin with 30.1 mg of this isotope, what mass remains after 44.6 days have passed?

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84. 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?

asked by Jacques on March 14, 2014
85. Chemistry

Mefenamic acid (Ponstan Forte) has a half life of 2 hours. Naproxen has a half life of 12 to 17 hours. Both are anti inflammatory drugs of apparently similar nature but could someone please explain the difference in half life? Thank you Mike

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86. Chemistry

The half-life of iodine -131 is 16 days. If you start with 100 gram sample, how many half-lives have past when you have less than a gram left?

asked by Taylor on October 28, 2007
87. 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

asked by Anonymous on May 1, 2011
88. Science math

Suppose a laboratory has a 38 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 1104 days? How much polonium is in the sample 1104 days later?

asked by Joshua on January 7, 2013
89. science

Suppose a laboratory has a 31 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 966 days? How much polonium is in the sample 966 days later?

asked by Anonymous on March 19, 2013
90. sciencemath

Suppose a laboratory has a 31 g sample of polonium-210. The half-life of polonium-210 is about 138 days. How many half-lives of polonium-210 occur in 966 days? How much polonium is in the sample 966 days later?

asked by Anonymous on March 19, 2013
91. physics

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94. SCIENCE

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95. Chemistry 212

The isotope californium-252 has a half life of 162 days. How many days would it take for 61.7% of the original material to decay? I am using the equation t= (ln(nt/no))/ k and I am first solving for K using: k=(.693/t1/2) the suppose answer can range from

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96. Physics

The isotope, Carbon-14 emits beta radiation and has a half live of 5730 years. How long will it take for the amount of radiation this gives off to drop by a factor of 4?

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97. Chemistry

Po-210 Ia an alpha emitter with a half-life of 138 days. how many grams of Po-210 remain after 552 days if the sample initially contained 5.80g of Po-210?

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98. Chemistry

Compute the volume of helium at 1.0 atm and 298 K that will be collected if 2.5 g of 222Rn is stored in a container able to expand to maintain a constant pressure for 15 days. Assume that 222Rn decays to 218Po with a half-life of 3.824 days.

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100. Engineering Math

An unknown radioactive element decays into non-radioactive 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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