Question

After 300 days, the activity of a radioactive sample is 5000 dps (disintegrations per sec). The activity becomes 2500 dps after another 150 days. The initial activity of the sample in dps is
A. 20000
B. 10000
C. 7000
D. 25000

Answer 1

Correct Answer - A
As, activity droped from 5000 dps to 2500 dps in 150 days means `T_(1//2)=150"days"`
`implies300"days"=2T_(1//2)`
So, initial activity `2xx5000xx2=20000` dps