The activity of a sample of radioactive material `A_(1)` at time `t_(1)` and `A_(2)` at time `t_(2)(t_(2)gtt_(1))`. Its mean life is `T`.

Options

A. `A_(1)t_(1)=A_(2)t_(2)`
B. `(A_(t)-A_(2))/(t_(2)-t_(1))="constant"`
C. `A_(2)=A_(1)e^(((t_(1)-t_(2)))/(T))`
D. `A_(2)=A_(1)e^((t_(1)//t_(2)//T)`

Answer

C

Explanation

`A_(1)=A_(0)e^(-lambdat_(1))` and `A_(2)=A_(0)e^(-lambdat)`
Dividing both, we get `lambda` and mean life is `(1)/(lambda)`