The activity of a radioactive elemment decreses to oen-third of the original activity `A_(0)` in a period of `9` years. After a further lapse of `9` years, its acticity will be

Options

A. `I_(0)`
B. `(2//3)I_(0)`
C. `(I_(0)//9)`
D. `(I_(0)//6)`

Answer

c

Explanation

`(A)/(I_0) =((1)/(3))^(2)=(1)/(9)` or `A=(I_(0))/(9)`.