# Element x Isotope 55x 60% Isotope 56x 30% Isotope. 57x 10% 55× 60 =3300 56×30=1650 57× 10= 570 Add them up5520 divide by 100 the atomic weight of x is 55.2 Pls check if this is correct , answer and

3,167 results
1. ## Chemistry

On another planet, the isotopes of titanium have the following natural abundances. Isotope 46Ti Abundance 70.900% Mass(amu) 45.95263 Isotope 48Ti Abundance 10.000% Mass(amu) 47.94795 Isotope 50Ti Abundance 19.100% Mass(amu) 49.94479 What is the average

2. ## Differential Equations

Model radioactive decay using the notation t = time (independent variable) r(t) = amount of particular radioactive isotope present at time t (dependent variable) -λ = decay rate (parameter) Note that the minus sign is used so that λ > 0 a) Using this

3. ## Chemistry

A SAMPLE OF ANTIMONY, Ar=121.8, WAS ANALYSED AND WAS FOUND TO CONSIST OF 60% OF 121Sb AND ONE OTHER ISOTOPE. DETERMINE THE MASS NUMBER OF THE OTHER ISOTOPE IN THE SAMPLE OF ANTIMONY. please help I'm really stuck,

4. ## math

Complete the table for the radioactive isotope. (Round your answer to two decimal places.) Isotope: 239Pu Half-life (years): 24,100 Initial Quantity: g Amount After 1000 Years: 0.6

5. ## Chemistry

A fictitious element X is composed of 10.0 percent of the isotope 55^X , 20.0 percent of the isotope 56^X , and 70.0 percent of the isotope 57^X . Calculate the weighted atomic mass of element X to the nearest tenth.

6. ## Chemistry

write isotpoic symbols of the form X-A (for example, C-13) for each of the following isotopes. **Do I add the number of protons and neutrons together to get the answer? The symbol is easy to figure out.** a) the iodine isotope with 74 neutrons B) the

7. ## Chemistry

1. A hypothetical pure element consists entirely of two isotopes. The natural percent abundance of the isotope with mass 25.5 u is 86.1%. The other isotope has mass 29.2 u. Calculate the atomic weight of the naturally occurring element. 2. Suppose that a

8. ## chemistry

One isotope of a nonmetallic element has mass number 16 and 7 neutrons in the nucleus. The anion derived from the isotope has 10 electrons. Write the symbol for this anion. I thought the answer was O^2- but this isnt correct

9. ## Chemistry

Cobalt-60 is a radioactive isotope used to treat cancers. A gamma ray emitted by this isotope has an energy of 1.33 MeV (million electron volts; 1 eV = 1.602 multiplied by 10-19 J). What is the frequency (in Hz) and the wavelength (in m) of this gamma ray?

10. ## Chemistry/Physics

"Colbalt-60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this isotope has an energy of 1.33 MeV (million electron volts; 1 eV = 1.602*10^-19 J). What is the frequency (in Hz) and

11. ## chem

Consider the isotope arsenic-76 How many protons are in an atom of this isotope? 33 What is the mass number of this isotope? 76 How many neutrons are in an atom of this isotope? 43 What is the atomic number of this isotope? 33 Give the nuclear symol 76/33

12. ## Chemistry

Gallium65, a radioactive isotope of gallium, decays by first order-kinetics. The half-life of this isotope is 15.2 min. How long would it take for 7/8 of a sample of this isotope to decay? 15.2 min 30.4 min 45.6 min 48.0 min I'm not sure how to do this. I

13. ## 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

14. ## Calculus

The rate of decay is proportional to the mass for radioactive material. For a certain radioactive isotope, this rate of decay is given by the differential equation dm/dt = -.022m, where m is the mass of the isotope in mg and t is the time in years. A. If

15. ## chemistry

one isotope of chromium (atomic number 24) has an atomic mass of 53 amu. how many neutrons are in this particular isotope of chromium? A. 24 B. 29 C. 53 D. 77 I say A

16. ## chemistry

One isotope of a metallic element has mass number 59 and 31 neutrons in the nucleus. The cation derived from the isotope has 26 electrons. Write the symbol for this cation.

17. ## 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

18. ## math

3. Write the exponential growth function to model the following situation: A population of 422, 000 increases by 12% each year. 4. At t = 0 there are 50 grams of a radioactive isotope. The isotope has a half-life of 16 minutes. Use the exponential decay

19. ## Math

An isotope of sodium has a half-life of 20 hours. Suppose an initial sample of this isotope has mass 10 grams. The amount of the isotope (in grams) remaining after t hours is given by: (Note: We're assuming exponential decay here. Use the exponential decay

20. ## astronomy

The isotope potassium-40 (40K) decays into the isotope argon-40 (40Ar) with a half-life of 1.25 billion years. Suppose we find a rock in which seven-eighths of the potassium-40 has decayed to become argon-40, and only one-eighth of the original

21. ## Chemistry

An element consists of 1.40% of an isotope with mass 203.973 amu, 24.10% of an isotope with mass 205.9745 amu, 22.10% of an isotope with mass 207.9766 amu. Calculate the average atomic mass and identify the element

22. ## 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?

23. ## mathematics

The exponential formula for the half-life of a radioactive isotope is y=y0ekt, where y is the amount of the isotope remaining after t years, y0 is the initial amount of the isotope, k is the decay constant, and e is the transcendental number approximately

24. ## Chemistry

An isotope, X, of a particular element has an atomic number of 15 and a mass number of 31. Which of the following statements are true? I. X is an isotope of phosphorus. II. X has 16 neutrons per atom. III. X has an atomic mass of 30.973

25. ## physics

The half-life of the plutonium isotope is 24,360 years. If 10 grams of plotonium is released into the atmosphere by a nuclear accident, how many years will it take for 80% of the isotope to decay?

26. ## Math help

Gold (Au) has a synthetic isotope that is relatively unstable. After 25.5 minutes, a 128-gram sample has decayed to 2 g. What is the half-life of this isotope? 8.5 minutes 2.25 minutes 1.5 minutes 4.25 minutes

27. ## Chemistry

I've figured out most of it. I'm not sure how to find the percentage ofd the isotope. Define the half life. The half-life of a radioisotope is found to be 4.55 minutes. If the decay follows first order kinetics, what percentage of isotope will remain after

28. ## chemistry ASAP

calculate the average atomic mass of element x in which the first isotope found in 28.5% abundance weighs 200.0 amu and the other isotope weighs 220.0 amu.

29. ## Chemistry

How to solve this: One isotope of a metallic element has mass # of 65 and 35 neutrons in nucleus. The cation derived from the isotope has 28 electrons. Write the symbol for this cation. Would the symbol be Cu? because Atomic # = protons = electrons and

A radioactive isotope source has a mass of 120ug. If the isotope had a half life of 20s, what would be the mass if the isotope after 2 mins?

31. ## Calculus

My teacher wants me to use this formula for half life question C(t) = Ce^-kt but i used a different formula plz help. the question is: A radioactive isotope has a half life of 30 years. If we started off with 10 mg of this isotope 12 years ago: a) Find and

32. ## chem

one isotope of carbon has the atomic # 6+ the mass #14. An Atom of this isotope contain how many elctrons

33. ## Science chemistry

It takes 1 hour and 17 min. for a 1.000gsample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp

34. ## Isotopes

I have an isotope, 292 uuh 116 this suffers seven successive alpha decay reactions, I know each for alpha decay reaction the isotope loses 4 He 2 so the atomic weight decreases by four, and the atomic number by 2... None of the elements shown in the

35. ## physics

in an initial mass of 40g, how much mass Remaining of the Isotope Approximately how much mass remains after 8.0 hours? After 21 hours, and what is the half life of the isotope

36. ## Chemistry

The isotope caesium-137, which has a half life of 30 years, is a product of neuclear power plants. How long will it take for the amount of this isotope in a sample of caesium to decay to one sixteenth of its original amount. Explain answer 30 years 1/2 60

37. ## 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

38. ## Chemistry

A hypothetical pure element consists entirely of two isotopes. The natural percent abundance of the isotope with mass 25.5 u is 78.8 percent. The other isotope has mass 29.5 u. Calculate the atomic weight of the naturally occurring element.

39. ## chemistry ASAP

calculate the average atomic mass of element x in which the first isotope found in 28.5% abundance weighs 200.0 amu and the other isotope weighs 220.0 amu.

40. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

41. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

42. ## chemistry

It takes 1 hour and 17 min. for a 1.000g sample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp

43. ## chemistry

A radioactive isotope of radium (Ra-226) has a half-live of 1620 years. How much of this isotope remains after three (3) half-lives? A. 1/2 B. 1/4 C. 1/8 D. None would this be C? please explain, thank you!

44. ## chemistry

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

45. ## Physics check

A certain radioactive isotope has a half-life of one hour. At noon, 100g of the material is present. How much of the original isotope will be present at 3:00 p.m.----1/8 6:00 p.m.-----1/16 10:00 p.m.-----1/32 Are these correct?

46. ## Chemistry

If a 100.0 gram sample of a radioactive isotope goes through three half-lives, how much of the original radioactive isotope will remain?

47. ## Chemistry

The strontium-90 isotope decays by the reaction below. It has a half-life of 28 yr. If the initial activity of this isotope was 168dpm, what would the activity be after 28.0 yr?

48. ## chemistry

Cobalt-60 is radioactive isotope used to treat cancers. A gamma ray photon emitted by this isotope has an energy of 2.13 x 10—13 J. What is the wavelength of this gamma ray in SI unit?

49. ## Calculus

A radioactive isotope has a half life of 25 years. There was 100 mg of the isotope in 2005. (a) Find an expression for the amount of the isotope, A(t), that is still active using time t, measured in years since 2005. Your expression must be of the form

50. ## Science

If an unstable isotope contained 5 protons and 8 neutrons, how many neutrons would need to decay to make the unstable isotope stable?

51. ## Earth Science

If an unstable isotope contained 5 protons and 8 neutrons, how many neutrons would need to decay to make the unstable isotope stable? Please Help!

52. ## chemistry

Element x Isotope 55x 60% Isotope 56x 30% Isotope. 57x 10% 55× 60 =3300 56×30=1650 57× 10= 570 Add them up5520 divide by 100 the atomic weight of x is 55.2 Pls check if this is correct , answer and method

53. ## Chemistry

Element X has three isotopes Isotope 1 Isotope 2 Isotope 3 Mass 28 29 30 Abundance % 92.18 4.71 3.12 ii)Use the isotope abundances and masses to calculate the relative atomic mass of x. Quote your answer to one decimal place. ii) Identify Element X. Show

54. ## Chemistry

A fictitious element X is composed of 78.0% of the isotope X-50, 15.0% of the isotope X-51 , and 7.0% of the isotope X-52. Estimate the atomic mass of element X. Show your work.

55. ## chemistry

A fictitious element X is composed of 70.0 percent of the isotope X^45, 20.0 percent of the isotope X^ 46, and 10.0 percent of the isotope X^47. Calculate the weighted atomic mass of element X to the nearest tenth. pls show all work

56. ## Chemistry

1.)Two different Isotopes are found to have 2 different cpm with Isotope A having a CPM that is 1.5x that of Isotope B? Which one is more radioactive? 2.) And how can CPM for an isotope be increased? I think that for the same CPM you can have different

How are the terms "activity" and "becquerel" related? A radioactive isotope source has a mass of 120 g. If the isotope has a half life of 20 secs what would be the mass of the isotope in 2 mins?

58. ## chemistry

A hypothetical pure element consists entirely of two isotopes. The natural percent abun- dance of the isotope with mass 25.6 u is 47.2%. The other isotope has mass 29.7 u. Calculate the atomic weight of the naturally occurring element.

59. ## Chemistry

Element L has an average atomic mass of 54.2488 amu and is composed of two isotopes. The first has a mass of 55.2036 amu and makes up 41.030% of a standard sample. What is the mass of the second isotope? I under how to get average atomic mass but not sure

60. ## 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

61. ## Calculus

A radioactive isotope has a half life of 25 years. There was 100 mg of the isotope in 2005. (a) Find an expression for the amount of the isotope, A(t), that is still active using time t, measured in years since 2005. Your expression must be of the form

62. ## Physics 30

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?

63. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

64. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

65. ## isd muscat

after two hours 1/16th of the radioactive isotope remains undecayed.half life of the isotope is

66. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

67. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

68. ## math

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.

69. ## Chem

The decay constant for a radioactive isotope is 7.82 x 10-6 /y. What is the half-life of this isotope in years?

70. ## Half-life

After two hours, 1/16 of the initial amount of a radioactive isotope remains undecayed. What is the half-life of the isotope?

71. ## Phys Sci

determine the isotope produced in the beta decay of iodine-131 an isotope used to check thyroid gland function

72. ## Physics

A certian radioactive isotope has a half-life 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?

73. ## Chemistry

Consider that: the tetravalent cation of an isotope has 78 electrons and 128 neutrons; Nuclear relative mass of the same cation is 1.44% higher than the relative nuclear mass of its most common isotope based on these data, calculate the number of neutrons

74. ## Chemistry

Consider that: the tetravalent cation of an isotope has 78 electrons and 128 neutrons; Nuclear relative mass of the same cation is 1.44% higher than the relative nuclear mass of its most common isotope based on these data, calculate the number of neutrons

75. ## math, calculus

A radioactive isotope has a half life of 25 years. There was 100 mg of the isotope in 2005. (a) Find an expression for the amount of the isotope, A(t), that is still active using time t, measured in years since 2005. Your expression must be of the form

76. ## geo/science

could you please tell me if this is the correct formula for radiometric date t=1/constant 1n (1+d/p) many thanks ps this is a fantastic website I think that you are after t=1/ë[ln(1+D/P)] where: t = age of the sample D = number of atoms of the daughter

77. ## Chemistry

A sample of a curium isotope was roasted. It was determined that the product( curium oxide) contained 11,59% of oxygen.¿ What is the equivalent weight of the isotope in the oxide? ¿ What is the mass of the curium isotope? I have already gotten the answer

78. ## Calculus

A radioactive isotope has a half life of 25 years. There was 100 mg of the isotope in 2005. (a) Find an expression for the amount of the isotope, A(t), that is still active using time t, measured in years since 2005. Your expression must be of the form

79. ## Science

9. Assume you began with 10 g of a radioactive parent isotope. How many grams of parent isotope will be present in the same sample after 2 half-lives? A. 5.0 g B. 2.5 g C. 1.25 g D. 0.63 g Is it A???

A radioactive isotope of radium (Ra-226) has a half-live of 1620 years. How much of this isotope remains after three (3) half-lives? A. 1/2 B. 1/4 C. 1/8*** D. None

81. ## 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?

82. ## College Geology

assume that a particular radioactive-isotope has a half-life of 100 million years. Also assume that the parent isotope is incorporated into the minerals found in igneous rocks and that the only daughter atoms in the rock formed from the decay of the parent

83. ## science

1.Carbon-14 is a radioactive isotope. What is an isotope? What is the approximate half-life of carbon-14?

84. ## math

What is the figure that gives the half-life of the isotope in minutes to 4 significant figures? Exponential regression on a set of data, which gives the amount of atoms of a radioactive isotope remaining after a time X minutes, produced the following

85. ## chemistry

We have not even covered this material. Samples of 131I take 10 hours to prepare to ship. It takes 2 weeks to get to its destination. How much 131I must be produced to ensure the patient receives 8 grams of NaI using the 131I isotope in the compound? Does

86. ## statistics

I have tried for days to figure out how to work this problem. Please help show me how to find the answer. A particular radioactive isotope decays from 210 mg to 182.7 mg in 15 days. Find the half life of the isotope.

87. ## Biology

How do you determine how the age of a specimen where there is only 1/2 of the original Carbon14 isotope left? What if 1/2 of the original isotope was left? I cannot show my work because I do not know how to figure this out.

88. ## s103

the isotope caesium -137, which has a half life of 30 years, is a product of nuclear power plants. How long will it take for the amount of this isotope in a sample of caesium to decay to one sixteenth of its original amount? - explain answer 1/16 = 1/2^x

89. ## physics

Is copper (Cu) the same as copper64 (Cu64)? Cu64 is a radioactive isotope of copper. Its half life is 12.8 hours. During the few days it is around, it behaves chemically like any other copper isotope, but eventually it all turns into something else. The

90. ## Physics

1. A gold atom has a mass of 3.287 • 10-25 kg and is at rest. It emits an alpha particle that has a mass of 6.646 • 10-27 kg. In this process, the gold atom is transformed into an iridium isotope. The alpha particle has a speed of 3.40 • 106 m/s. A.

91. ## algebra

the isotope has a very short life of 13 half-life days. estimate the percentage of the original amount of the isotope released by the explosion that remains 3 days after the explosion?

92. ## Chemistry

If a radioactive isotope has a half life of 162 days how many half lives would it need to go through to have 50% of that isotope to be non-radioactive?

93. ## Alpha decay

Hi I am working on a question which discusses ununhexium atomic number 116 atom weight 292. This isotope undergoes 7 alpha decay reactions. I have calculated that after seven reactions the product would be 102 nobelium. I cannot understand how the atomic

94. ## science

what is the heaviest element that has only one isotope and is not radioactive?

95. ## chemistry

What is the heaviest element that has only one isotope and is not radioactive?

96. ## chem

The half-life of the Nobelium isotope No^257 is about 23 seconds. 644 seconds (or 28 half-life periods) after the isotope was released there were 20 grams remaining. The number of grans of No^257 after h half life periods is M= 20 * (1/2)^h where h = 0

97. ## modern physics

A radioisotope P has a half-life of 3 s. At t = 0, a given sample of this isotope contains 8000 atoms. Calculate (i) its decay constant, (ii) average life, (iii) the time t1 when 1000 atoms of the isotope P remain in the sample, and (iv) number of decays

98. ## 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

99. ## 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

100. ## 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