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9. If we start with 1.000 g Sr-90,0.953g remains after 2 years. A) Find the half

ID: 592330 • Letter: 9

Question

9. If we start with 1.000 g Sr-90,0.953g remains after 2 years. A) Find the half-life for Sr-90, and b) how much Sr-90 remains after 5 years?. 10. What is the mass defect, the nuclear binding energy per atom; and the binding energy per nucleon for U-2387(isotopic mass of U-238 = 238.05078 amu) 11, what is the mass defect in amu and in g/mol for O-17? (isotopic mass of O-17 = 16.9991312 amu; use the given masses of protons, neutrons, and electrons) 12. If a mass defect is 0.0 105 g/mol, what is the nuclear binding energy per mol?

Explanation / Answer

Ans 9 :

Using the half life formula :

Nt = No(1/2)t/ t 0.5

where Nt is the final amount of sample

No is the initial amount of sample

t is the amount of time lapsed

t 0.5 is the half life period

A) So putting all the values , we get :

0.953 = 1.000 (1/2)2/ t 0.5

t 0.5 = 28.797 years

B) Putting the values :

Nt = 1.000 (1/2)5 / 28.797

Nt = 0.887 grams