In one averge life - time of a radioactive nuclei,

Options

A. more than half the active nuclei decay.
B. half the active nuclei decay
C. less than half the active nuclei decay
D. all the nuclei decay

Answer

A

Explanation

key idea The mean life of a radioactive element is equal to the ratio of the sum of life - time of all the active atom to the total numbers of active atom. It can be expressed as
Mean life `(tau) =1/("decay constnat" (lambda))`
since, as we know that the half- life of radioactive nuclei is given as,
`T_(1//2) = (0.693)/(lambda)`
So, from above expression,
`T_(1//2) = 0.693 tau`
As 0.693 is less than 1 so the average life time is more than the half life of atom.