1.

The half-life of a radioisotope is 20 years. If the sample has an initial activity of 640 dps,than what will be its activity after 80 years?

Answer»

20 dps
30 dps
40 dps
50 dps

Solution :`t_(1//2) = 20 "years" , t = 80` years,
`N_0 = 640 dps, N_t = ?`
Number of half lives gone `(n) = (80/20)= 4`
Now, `N_t = N_0 XX (1/2)^(n) = 640 xx (1/2)^(4) = (640)/(16) = 40 dps`
The ACTIVITY of the radioisotope will be 40 dps after 80 years.


Discussion

No Comment Found

Related InterviewSolutions