A fraction `f_1` of a radioactive sample decays in one mean life, and a fraction `f_2` decays in one half life. Then

Options

A. `f_1 gt f_2`
B. `f_1 lt f_2`
C. `f_1=f_2`
D. either of (a),(b ) or (c ) depending on the values of the mean life and half life.

Answer

a

Explanation

Mean life, `tau=1/lambda`
and half life , `T_(1//2)="In2"/lambda=0.693/lambda`
`therefore tau gt T_(1//2)`. Greater fraction will decay in longer time. Hence, fraction decayed in one mean life must be greater than the fraction decayed in one half life i.e. `f_1 gt f_2`.