# What is the activity of a 18.9 μCi sample of carbon-14 in becquerels?

18,030 results
1. ## chemistry

A sample of propane(c3h8)has 3.84x10^24 H atoms. a) how many carbon atoms does the sample contain? b) what is the total mass of the sample?

2. ## chemistry

A wooden object from a prehistoric site has a carbon-14 activity of 10 counts per min.(cpm) compared to 40 cpm for new wood. If carbon-14 has a half life of 5730 years what is the age of the wood? Please get me started. Thank you

3. ## Chemistry

A sample of sodium-24 with an activity of 12 mCi is used to study the rate of blow flow in the circulatory system. If sodium -24 has a half-life of 15 hours, what is the activity of the sodium after 2.5 d ?

4. ## Chemistry

The cloth shroud from around a mummy is found to have a carbon-14 activity of 8.1 disintegrations per minute per gram of carbon as compared with living organisms that undergo 15.2 disintegrations per minute per gram of carbon. From the half-life for

5. ## chemistry

An unknown compound contains only carbon, hydrogen, and oxygen (CxHxOx). Combustion of 3.50G of this compound produced 5.13G of carbon dioxide and 2.10G of water A.How many moles of carbon, , were in the original sample? b. How many moles of hydrogen, ,

6. ## chemistry

When a 8.45-mg sample of a compound containing carbon is burned completely, 18.1 mg of carbon dioxide is produced. What is the mass percentage of carbon in the compound?

7. ## Chemistry

Carbon-14 has a half-life of 5730 y. How much of a 144 g sample of a carbon-14 will remain after 1.719 (times) 10 4y?

8. ## Chemistry

Complete combustion of a sample of propane produced 2.641g of carbon dioxide and 1.442g of water as the only products. Find the empirical formula of propane. I have already calculated the number of moles for both water and carbon dioxide. I also know that

9. ## Chemistry

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 After 22 min, 12.9 mL of blood was withdrawn from the man and the activity of that sample was

10. ## chemistry

A 25.002g sample of a compound that contains carbon, and hydrogen, is subjected to a complete combustion reaction. Analysis of the products of the reaction produced 76.392g of carbon dioxide and 37.504g of water. Determine the empirical formula for the

11. ## chemistry

Consider a sample of a hydrocarbon (a compound consisting of only carbon and hydrogen) at 0.959 atm and 298 K. Upon combusting the entire sample in oxygen, you collect a mixture of gaseous carbon dioxide and water vapor at 0.755 atm and 375 K. This mixture

12. ## physics

A wooden artifact is found in an ancient tomb. Its carbon-14 activity is measured to be 60.0% of that in a fresh sample of wood from the same region. Assuming the same amount of carbon-14 was initially present in the wood from which the artifact was made,

13. ## Finance

The projected revenues and costs that form the basis of the potential for a project's acceptance or rejection are estimates of ______________. A. Future activity B. Past activity C. Known activity D. Current activity

14. ## chem

A sample of carbon,3.0g, was burned to carbon dioxide in a copper calorimeter.The mass of the calorimeter was 1.5kg and the mass of water in the calorimeter was 2kg.The initial temperature was 20°c and the final temperature was 31°c.Calculate the heat

15. ## Chemistry

What is the activity of a 18.9 μCi sample of carbon-14 in becquerels?

16. ## Chemistry

The half-life of oxygen -15 is 124 seconds. If a sample of oxygen -15 has an activity of 4000 becquerels, how many minutes will elapse before it reaches an acivity of 500 becquerels

17. ## college Geol 101

Suppose you have a sample of clamshell at a Paleoindian site and you measure the 14C activity of a 100-gram sample of carbon as 320 disintegrations per minute (or 3.2 disintegrations per gram of carbon per minute). a.What was the activity (in

18. ## Chemistry

A sample of pure cobalt-60 has an activity of 8 µCi. (t1/2 cobalt-60 = 5.26 a) (a) How many atoms of cobalt-60 are present in the sample? atoms (b) What is the mass in grams of the sample? g The way I approached part a was to first convert the microCi

Beryllium-7 has a half-life 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

20. ## Physics

a piece of charcoal containing 25.0g of carbon is found in some remains of ancient city. The sample shows carbon 14 activity R of 250decays/min. How long has the tree from which this charcoal came from been dead?

21. ## science

The half-life of carbon 14 is 5730 years. if a 1 g sample of old carbon is 1/8 as radioactive as 1 g of a current sample, then the age of the old sample is about ___________years. 22,900 17,200 11,500 716

22. ## Physics

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

23. ## chemistry

A 1.00-g sample of carbon from a modern source gave 15.3 disintegrations per minute. A sample of carbon from an “old” source gave 920 disintegrations per hour. What is the age of the “old” sample of carbon? The half-life of carbon-14 is 5.73×103

24. ## children's literature

Creativity supports problem solving in children and is what type of activity? A. Cognitive activity B. Physical activity C. Social activity D. Emotional activity D?

25. ## Physics

(a)-A fossilised tree was tested and contains 10 grams of Carbon-14. Given that there was 12 grams of Carbon-14 present when it died, determine the age of the fossil? Half life of Carbon-14 is 5700 years. (b)How much Carbon-14 will be present in the sample

26. ## Physics

(a)-A fossilised tree was tested and contains 10 grams of Carbon-14. Given that there was 12 grams of Carbon-14 present when it died, determine the age of the fossil? Half life of Carbon-14 is 5700 years. (b)How much Carbon-14 will be present in the sample

27. ## Intermediate Maths

(a)-A fossilised tree was tested and contains 10 grams of Carbon-14. Given that there was 12 grams of Carbon-14 present when it died, determine the age of the fossil? Half life of Carbon-14 is 5700 years. (b)How much Carbon-14 will be present in the sample

28. ## Final Maths

(a)-A fossilised tree was tested and contains 10 grams of Carbon-14. Given that there was 12 grams of Carbon-14 present when it died, determine the age of the fossil? Half life of Carbon-14 is 5700 years. (b)How much Carbon-14 will be present in the sample

29. ## AP Chemistry

A sample of chloroform is found to contain 12.0 g of carbon, 106.4 g of chlorine, and 1.01 g of hydrogen. If a second sample of Chloroform is found to contain 30.0 g of carbon. what is the total mass of Chloroform in the second sample?

30. ## Chemistry

A 10.0 L vessel contains 0.0015 moles carbon dioxide and 0.10 moles of carbon monoxide. A 5.00 gram sample of carbon is added and the temperature is increased to 1000. degrees C. Will more carbon monoxide form? Kc at 1000 degrees C is 1.17. CO2(g) + C(s)

31. ## chemistry

The radioactive decay of carbon-14 is first-order and the half-life is 5800 years. While a plant or animal is living, it has a constant proportion of carbon-14 (relative to carbon-12) in its composition. When the organism dies, the proportion of carbon-14

32. ## Statistics

Williams, Dunsiger, Jennings, and Marcus (2012) conducted a study to test how enhanced mood during exercise can increase the likelihood of physical activity in the future. They reported that at 6 months of physical activity, mood scores (rated on a scale

33. ## chemistry

a sample of sodium-24 with an activity of 12 mCi is used to study the rate of blood flow in the circulatory system. If sodium-24 has a half-life of 15 h, what is the activity of the sodium after 2.5 days. please show work.

34. ## Chemistry

A chemist prepares a 45.0-g sample of carbon tetrachloride (CCl4). How many moles of this compound has she prepared? (Note: The atomic weight of carbon is 12.0 and of chlorine is 35.5.) how do i do this?

35. ## Chemistry

A sample of propane, C3H8, contains 10.0 moles of carbon atoms. How many total moles of atoms does the sample contain? Express the total number of moles of carbon and hydrogen numerically.

36. ## math

Suppose that drilling into what was once a lake bottom produces a piece of wood which, according to its mass, would have contained 5 nanograms (5 billionths of a gram) of carbon-14 when the wood was alive. Use the fact that this radioactive carbon decays

37. ## Physics

A sample of air contains 4.56 x 10^24 molecules of CO2. Calculate how many moles of carbon dioxide are in that sample.

38. ## Chemistry

One last question...even though no one seems to be willing to help me out without being rude. 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.

39. ## geology

suppose you have a sample of clamshell at a paleoindian site and you measure the 14c activity of aa 100-gram sample of carbon as 320 disintegretions per scond (or 3.2 disingtegrations per gram of carbon per second). a. what was the activity(in

40. ## college physics part 2

the activity of a sample of carbon has one-eighth of the initial activity. carbon-14 has a half-life of 5730 yr. how old is the sample in yr?

41. ## physics 2

A sample has a activity of 0.0065 Bq per gram of carbon. (a) Find the age of the sample, assuming that the activity per gram of carbon in a living organism has been constant at a value of 0.23 Bq. (b) Evidence suggests that the value of 0.23 Bq might have

42. ## physics

A sample has a activity of 0.0065 Bq per gram of carbon. (a) Find the age of the sample, assuming that the activity per gram of carbon in a living organism has been constant at a value of 0.23 Bq. (b) Evidence suggests that the value of 0.23 Bq might have

43. ## college geology help please

I was the same person from yesterday. I need help on a question. I don't type very good so I have one of my host family do it for me. so please help us. Suppose you have a sample of clamshell at a Paleoindian site and you measure the 14C activity of a

44. ## chem

A 73-kg person is accidentally exposed for 215 s to a 16-mCi source of beta radiation coming from a sample of 14C. What is the activity of the radiation source in disintegrations per second? In becquerels? i am not sure if there is an equation for this or

45. ## chem

I am not sure if there is an equation for this problem or wut?? A 73-kg person is accidentally exposed for 215 s to a 16-mCi source of beta radiation coming from a sample of 14C. What is the activity of the radiation source in disintegrations per second?

46. ## Physicr

A 10 kg sample from a living plant has actiuity 30 000 Bq due to Carbon-14. A 500g sample of the same type of plant but dead has activity 1 000 Bq. Calculate the age of the dead sample given that the half life of Carbon-14 is 5568 years

47. ## ChemB

The activity of carbon 14 in living tissue is 15.3 disintegrations per minute per gram of carbon. The limit for reliable determination of age is based on carbon 14 is .10 disintegration per min per gram of carbon. Calculate the max age of a sample that can

48. ## physics

before 1900 the activity per mass of atmospheric carbon due to the presence of carbon-14 averaged about 0.255bq/g of carbon 1. what fraction of carbon is carbon-14

49. ## physics

before 1900 the activity per mass of atmospheric carbon due to the presence of carbon-14 averaged about 0.255bq/g of carbon 1. what fraction of carbon is carbon-14

50. ## chemistry

The amount of organic carbon in a sample can be obtained by IR analysis of the carbon dioxide (CO2) released following complete combustion of the sample in oxygen. A reference sample of an organic compound is usually used to calibrate the instrument

51. ## Calculus

The amount of carbon-14 still present in a sample after t years is given by the function where C0 is the initial amount. Estimate the age of a sample of wood discovered by an archeologist if the carbon level in the sample is only 18% of its original

52. ## chemistry

A 1.00-g sample of carbon from a modern source gave 15.3 disintegrations per minute. A sample of carbon from an “old” source gave 920 disintegrations per hour. What is the age of the “old” sample of carbon? The half-life of carbon-14 is 5.73×103

53. ## chemistry

Assayed for LDH activity were 5 microliters of a sample that was diluted 6 to 1. The activity in the reaction vessel, which has a volume of 3 mililiters, is 0.30 U. What is the ΔA/min observed? What is the relative activity of the original sample? Here

54. ## Physics

When any radioactive dating method is used, experimental error in the measurement of the sample's activity leads to error in the estimated age. In an application of the radiocarbon dating technique to certain fossils, an activity of 0.15 Bq per gram of

55. ## 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?

1. A granite rock is thought to be about 2 billion years old. why is it not possible to determine the age of the Rock using carbon-14 dating? 2. A hair sample has 80% of its original carbon-14 present. what is the age of the sample? 3. A bone fragment has

57. ## Chem

If you have a 12.01g sample carbon. What would be the average mass of a carbon atoms if it is 1.994 x 10 to the 23 power g. How many carbon atoms are in the sample?

58. ## nuclear physics

Calculate the age of a plant sample that shows about one-eighth of the carbon 14 of a living sample. The half-life of carbon 14 is about 5760a How do you do this?

59. ## nuclear

Calculate the age of a plant sample that shows about one-eighth of the carbon 14 of a living sample. The half-life of carbon-14 is about 5760 a. Help please...

60. ## physics

How do I do this ? Calculate the age of a plant sample that shows about one-eigth of the carbon 14 of a living sample. The half-life of carbon-14 is about 5760a I don't have the notes on how to do this one... Help

61. ## chemistry

You have a 12.01 g sample of carbon. The average mass of a carbon atoms is 1.994 x 1023 g. How many carbon atoms are in the sample?

The activity of a sample of Ba-137m has decreased by 75% from its initial activity after 5.10 minutes. What is the half-life of Ba-137m? What fraction of activity remains after 6.25 minutes? (A=Aoe (-kt); k = .693/t1/2)

63. ## Chem

Living organisms give a Carbon-14 decay rate of 15.3 counts/min for each gram of carbon in the sample. A sample of bristle cone pine wood has a decay rate of 3.20 counts/min per gram of carbon. Calculate the age of the wood from the radiochemical evidence.

64. ## psychology

Leigh, B. C. (1993). Alcohol consumption and sexual activity as reported with a diary technique. Journal of Abnormal Psychology, 102, 490-493. doi:10.1037/0021-843X.102.3.490 This is the article to utilize when answering the questions 1. What are the

65. ## biology- photosynthesis

There is a distinct oscillation of CO2 during each year as CO2 is added to the atmosphere each winter or removed from the atmosphere each summer. Explain what specific cellular processes lead to these changes in CO2 level. You must explain what causes CO2

66. ## chem

Hi the following comes from my first homework assignment in AP Chemistry. I am totally lost on this question and don't know where to start. Thanks a lot in advance!!!!! A 0.1247 g sample of ascorbic acid, Vitamin C, was burned in a carbon-hydrogen

67. ## Chem Need Help

I really need help with this question? You have a 12.01 g sample of carbon. The average mass of a carbon atoms is 1.994 x 1023 g. How many carbon atoms are in the sample? (round the number to 2 decimal places) (if you get a superscript, place a ^ before

68. ## Chemistry

A sample of .234g of carbon is placed in a closed stainless steel bomb with .502g of of oxygen gas. The mixture is ignited giving of carbon dioxide. How many grams of carbon dioxide should be obtained upon combustion?

69. ## chem

A sample of radon has an activity of 80,000 Bq. If the half-life of radon is 15 h, how long before the sample's activity is 5,000 Bq?

70. ## Calculus

The quantity Q of radioactive carbon remaining in a 200-gram 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

71. ## Pre-Cal

A piece of charcoal of mass 35g is found in the ruins of an ancient city. The sample shows a carbon-14 activity or R(t)=4.167 decays/sec. Convert the decay constant of ^14C from (1)(a)in terms of seconds instead of yrs. Find the number of atoms N(t)using

72. ## chem

the half life of oxygen-15 is 124 s. if a sample of oxygen-15 has an activity of 4000 Bq, how many minutes will elapse before it reaches an activity of 500Bq

73. ## chemistry

The half-life of oxygen-15 is 124 s. If a sample of oxygen-15 has an activity of 4800 Bq, how many minutes will elapse before it has an activity of 600 Bq?

74. ## Chemistry

Write mathematical equations that show how you will calculate the detected activity from the count rate due to background radiation and the sample of KCl and how you will determine the “true” activity of your sample from the detected activity. Use the

75. ## college geology dealing with carbon 14

ok in my professors notes he calculates carbon 14 age in an example. The problem goes like this: Sample contains 110g carbon sample produces 70 disintegrations per minute. That is 0.7 disintegrations per minute. T=(1/lambda)ln(N0/Nt) Then he substitutes:

76. ## Physics

The activity of a sample of 31Si (T1/2 = 9.43×103 s) is 7.88×105 decays per second. What is the mass of sample present?

77. ## Chemistry

A 100.00g sample of the gaseous hydrocarbon ethane is a gaseous hydrocarbon, with 79.89g of carbon and 20.11g of hydrogen. Ethylene is a different gas phase hydrocarbon. A 100.00g sample of ethylene has 85.63g of carbon with 14.37 of hydrogen. A sample of

78. ## Chemistry

7. A 100.00g sample of the gaseous hydrocarbon ethane is a gaseous hydrocarbon, with 79.89g of carbon and 20.11g of hydrogen. Ethylene is a different gas phase hydrocarbon. A 100.00g sample of ethylene has 85.63g of carbon with 14.37 of hydrogen. A sample

79. ## science

if a sample of rock starts out with 32 atoms of carbon-14 how much carbon-14 would be left after 5,700 years

80. ## Chemistry

Carbon-14 has a half-life of 5730 y. How much of a 144 g sample of a carbon-14 will remain after 1.719 (times) 10 4y?

81. ## Physics Plz help me

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)

82. ## Physics!

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)

83. ## Physics Plz help me

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)

84. ## Physics

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)

85. ## chemistry

A sample of carbon dioxide has a mass of 47.4 g. How many carbon atoms are present?

86. ## Nuclear physics Repost

1) An old wooden tool is found to contain only 11.9 percent of 14C that a sample of fresh wood would. How many years old is the tool? 2) A specimen taken from the wrappings of a mummy contains 7.02 g of carbon and has an activity of 1.34 Bq. How old is the

87. ## Nuclear physics

1) An old wooden tool is found to contain only 11.9 percent of 14C that a sample of fresh wood would. How many years old is the tool? 2) A specimen taken from the wrappings of a mummy contains 7.02 g of carbon and has an activity of 1.34 Bq. How old is the

88. ## chemistry

Suppose a substance has been prepared that is composed of carbon, hydrogen, and nitrogen. When 0.1156 gram of this compound is reacted with oxygen, 0.1638 gram of carbon dioxide (CO2) and 0.1676 gram of water (H2O) are collected. Assuming that all the

89. ## Math

The quantity Q of radioactive carbon remaining in a 300 - gram wood sample at time t is given by the expression Q(t) = 300 e^{- 0.000324*t}. How much radioactive carbon remains in the sample after (a) 200 years, (b) 50000 years, (c) 125500 years?

90. ## chemistry

A 2.760 g sample of carbon was burned, yielding 10.120g of carbon dioxide. How many grams of oxygen was taken up by the reaction? What ofrmula would I use to solve this problem?

91. ## chemistry

If 20 L of O2 burns completely a sample of carbon disulfide, how many liters of carbon dioxide are produced, how many liters of carbon dioxide are required?

92. ## chemistry

If 20 L of O2 burns completely a sample of carbon disulfide, how many liters of carbon dioxide are produced, how many liters of carbon dioxide are required? How did you get 16?

93. ## physics

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

94. ## 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.

95. ## 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 half-life of this material? (in days)

96. ## chemistry

a 2.52-g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess O to yield 4.23 g of CO2 and 1.01 g of H2O as the only carbon and hydrogen containing products respectively. Another sample of the same

97. ## chemistry

1) 4.20 x10^6 ml + 12.3 x 10^2 L= My answer is 4.21 x 10^9 2) Change 17.7 L to cubic meters? My answer 1.77 x 10^3 3) Draw an electron dot diagram for K3PO3 My answer K O P O O I couldn't do the dots but there should be 26 dots right? 4) A 35.0 g sample of

98. ## Chemistry

A certain Geiger counter is known to respond to only 1 of every 1000 radiation events from a sample. Calculate the activity of each radioactive source in curies, given the following data. My text barely attempts to explain how to do this problem, and there

99. ## Chemistry

A sample of toluene, C7H8 has a mass of 74.5 g. a) how many molecules does the sample contain? b) How many carbon atoms does it contain? How many hydrogen atoms does it contain? My work For b would it be 7 carbon atoms and 8 hydrogen atoms

100. ## Chemistry

A sample of calcium carbonate that has a mass of 1.0 g is heated and completely decomposed-calculate. a) the mass of carbon dioxide produced b)the volume of carbon dioxide at SLC c)the volume of carbon dioxide at STP