Question 4 (3 points) A 210Po source with a half life of 138.4 days was calibrat

Question

Question 4 (3 points) A 210Po source with a half life of 138.4 days was calibrated at 0.1 HCi, 3 years ago. Under your detector it records 2.16 x 103 cpm. What is your detector's percent efficiency? Save Question 5(3 points) What is the mass of 1.00 HCi of 22Na whose half life is 2.6 years? Save Question 6 (2 points) During manufacture, a radioactive sample contains 2 x 1011 atoms. After 60 days, the sample contains 5.2 x 103 atoms. Determine the half life of the sample. Save Save All Responses Go to Submit Quiz

Explanation / Answer

(Q6)

Ans

According to the concept of the nuclear physics

Given that

Initial number of the Atoms No=2*10^11 atoms

Number of the atoms after 60 days=>N=5.2*10^3 atoms

Time t=60 days

Basing on the concept of the law of the radio active decay law

N=No(1/2^n)

2^n=No/N

Apply 'log ' on both sides

n*Log(2)=Log(No/N)

t/T1/2*log(2)=Log(2*10^11/5.2*10^3)

t/T1/2 *0.3010=7.56

60/T1/2=(7.6/0.3010)=25.25

T1/2=60/25.25=2.4 days

Therefore the half life of the sample =2.4 days

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