HALF-LIFE TIME

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.

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 radioactive sample decays through two different decay processes alpha -decay and beta -decay. Half-life time for alpha −decay is 3h and half-life time for beta −decay is 6h . What will be the ratio of number of initial radioactive to the number of nuclei present after 6 h ?.

Statement-1: For A+2BtoC (rate = K[A]^(1)[B]^(0) ), the half life time of reaction is only defined when concentration of A and B are in stoichometric ratio Statement-2 :For above reaction, half life of reaction is directly proportional to concentration of A and not to concentration of B due to its zero order.

Define the terms: Half-life period and reaction life time.