Question

a pure sample of a radioactive substance has 16*10^12 atoms and the half life is 3...

a pure sample of a radioactive substance has 16*10^12 atoms and the half life is 3 minutes. How long does it take until 5*10^11 atoms of the substance have not yet decayed?

Homework Answers

Answer #1


Given
  

   pure radio active substance initially N0 = 16*10^12 atoms are there


   half life time T1/2 = 3 min = 180 s

  

we know that T1/2 = 0.693/ Lambda LAmbda is decaay constant


   lambda = 0.693/180 = 0.00385 desintigrations per sec

   and the relation N = N0 e^(-Lambda*t)

  

           5*10^11 = 16*10^12*e^(-0.00385*t)

           t = 900.191 s
           t = 15 min

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
A sample of radioactive nuclei initially contains 6.00 ×1010×1010 radon atoms. The half-life of this type...
A sample of radioactive nuclei initially contains 6.00 ×1010×1010 radon atoms. The half-life of this type of nucleus is 500 days. How many nuclei have decayed after 167 days? A sample of radioactive nuclei initially contains 6.00  radon atoms. The half-life of this type of nucleus is 500 days. How many nuclei have decayed after 167 days? 2.00×1010 4.00×1010 1.24×1010 4.76×1010
A sample of radioactive nuclei initially contains 9.00 ×1010 radon atoms. The half-life of this type...
A sample of radioactive nuclei initially contains 9.00 ×1010 radon atoms. The half-life of this type of nucleus is 450 days. How many nuclei have decayed after 150 days? OPTIONS: 7.14×1010 6.00×1010 3.00×1010 1.86×1010
A radioactive nuclide has a half-life of 30.7 y. What fraction of an initially pure sample...
A radioactive nuclide has a half-life of 30.7 y. What fraction of an initially pure sample of this nuclide will remain undecayed at the end of 86.8 y?
1. The half-life single radioactive nuclei is 10 years. When will this nuclei decay? 2. The...
1. The half-life single radioactive nuclei is 10 years. When will this nuclei decay? 2. The half-life of radioactive nuclei is 20 years. How much time must pass before 50% of the nuclei have decayed? _____75 years?
Radioactive Half-life Years Element A Remaining Radioactive Atoms Element B Remaining Radioactive Atoms Element C Remaining...
Radioactive Half-life Years Element A Remaining Radioactive Atoms Element B Remaining Radioactive Atoms Element C Remaining Radioactive Atoms Element D remaining Radioactive Atoms 0              100 100 100 100 1000 50 85 90 95 2000 25 72 81 90 3000 13 61 73 86 4000 6 52 66 81 5000 3 44 59 77 6000 2 38 53 74 7000 1 32 48 70 8000 0 27 43 66 9000 0 23 39 63 10000 0 20 35 60 11000...
Consider a sample of 12 grams of 18F with an activity of 640 kBq. The half-life...
Consider a sample of 12 grams of 18F with an activity of 640 kBq. The half-life of fluorine-18 is about 20 minutes. (g) [2 points] What is the mass of the sample (in grams) after 1 hour? (h) [2 points] What is the activity of the sample (in kBq) after 1 hour? (i) [3 points] How many minutes does it take for the sample to be 90% less radioactive? In other words, how many minutes does it take for the...
Part A You are using a Geiger counter to measure the activity of a radioactive substance...
Part A You are using a Geiger counter to measure the activity of a radioactive substance over the course of several minutes. If the reading of 400. counts has diminished to 100. counts after 78.4 minutes , what is the half-life of this substance? Express your answer with the appropriate units. Part B An unknown radioactive substance has a half-life of 3.20 hours . If 26.8 g of the substance is currently present, what mass A0 was present 8.00 hours...
An unknown radioactive substance has a half-life of 3.20 hours . If 38.3 g of the...
An unknown radioactive substance has a half-life of 3.20 hours . If 38.3 g of the substance is currently present, what mass A0 was present 8.00 hours ago?
1. a) If a radioactive substance has a half-life of one year, does this mean that...
1. a) If a radioactive substance has a half-life of one year, does this mean that it will be completely decayed after two years? Explain     b) Many individuals carry recessive gene for albinism but they are not albino unless they recieve the gene from both their parents. In the U.S., an individual`s probability of recieving the gene from a given parent is about 0.014. What is the probability that a given child will be born albino?    c) Devise...
You have a sample of a radioactive material with a half-life of 5.0 years that has...
You have a sample of a radioactive material with a half-life of 5.0 years that has a current activity of 0.12 µCi. The sample has a label on it which indicates that when it was first manufactured it had an activity of 3.84 µCi. How long ago was the sample manufactured? (to 2 s.f and in years)
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT