Question

Many unstable nuclie can decay spontaneously to a nucleus of lower mass but differnet combination of nucleons. The process of spontaneous emission of radiation is called radioactivity substance.
Radioactive decay is a statistical process. Radiaactivity is independent of all external conditions. The number of decays per unit time or decay rate is called activity. Activity exponentially decrease with time. Mean lifetime is always greater than half-life time.
If `T_(H)` is the half-life and `T_(M)` is the mean life. Which of the following statement is correct.
A. `T_(M) gtT_(H)`
B. `T_(M)ltT_(H)`
C. Both ar directly proportional to square of the decay constant.
D. `T_(M) prop lambda_(0)`

Answer 1

Correct Answer - a
`T_M =(1)/(lambda)` and `T_(H) =(0.693)/(lambda)`
Now, `(T_(M))/(T_(H))=(1)/(lambda) xx (lambda)/(0.693)=(1)/(0.693)`
i.e.,
`T_(M) gt T_(H)`
From the above explanation, it is clear that choice (a) is correct and other (b), ( c) and (d) are wrong.