What percentage of strontium-90 remains in a sample after three half-lives have passed?

Answer 1

http://www.Google.com/url?q=http://www.answers.com/topic/strontium-90-2&ei=JG7qSM2YMJr0sAOwisShCg&sig2=gkRoGShTOIIyl_qP_wHqOA&sa=X&oi=answers&ct=result&usg=AFQjCNGhe0i2Llp-0PI58ffJwNxGpKIeEg - Half-Life: 28.8 Years

Answer 2

Since the half life of Strontium-90 is 28.8 years, there will be about 16% of the sample remaining as strontium-90 after 75.0 years. This is 2.6 half-lives, and the proportion remaining is 2-(75/28.8).

Of coarse the rest of the sample will still be there, but it will have become yttrium-90.

Answer 3

you will use this formula: A=Pe^(k*t). A=amount of material, P= the initial amount of material, k=the decay rate, t=time

first you must solve this equation for k: 1=2e^(k*29)

then you will plug you k into this equation: (.2)P=Pe^(k*t)--- your P's cancel, and you are left with (.2)=e^(k*t). then, take the natural log of both sides. that will allow you to bring the exponent down and solve for t.

Answer 4

a) I find 0.625 mg, that is 10/(2**(114/28.5)), that is 10/16

b) I find 1.5 Bq, that is 24/16

Answer 5

56 Years.

The Half life is 28 years. So 68/2=34=28 years. 34/2=14=28 years. 28 years + 28years = 56 years

Answer 6

Approox. 18 %.

Answer 7

0.5*0.5*0.5 = 0.125 = 12.5%

Answer 8

13.6

Answer 9

t = 28.7yrs

Answer 10

56