Question

If one starts with 1 curie of radioactive substance `(t_(1//2) = 12 h)`, the activity left after a period of 1 week will be about
A. 1 curie
B. 129 microcurie
C. 60 microcurie
D. 8 millicurie

Answer 1

Correct Answer - c
Given, `t_(1//2) = 12 h`.
t = 1 week `= 7xx24h, N = N_(0)((1)/(2))^((t)/(t_(1//2))) = 1xx((1)/(2))^((7xx24)/(12))`
`=((1)/(2))^(14) = 6.1xx10^(-5)` curie = 60 microcurie