Question

A fraction $f_1$ of a radioactive sample decays in one mean life and a fraction $f_2$ decay is one half-life then which of the following relation is true?

• A. $f_1>f_2$
• B. $f_1<f_2$
• C. $f_1=f_2$
• D. May be (a), (b) or (c) depending on the values of the mean life and half-life

Answer 1

The correct option is A $f_1>f_2$

Mean life is equal to 1.443xhalf-life

So the time span of 1 mean-life is more than that of 1 half-life.

Thus, number (and fraction) of radioactive sample decay would be more in 1 mean-life than that in 1 half-life.

So, $f_1>f_2$