Question

The number fo radioactive atoms of a radio isotope fails to `12.5%` in 27 day. Calcualate the half-life of isotope.

Answer 1

Correct Answer - `9`
`lambda = (2.303)/(t) log (N_(0))/(N)`
`= (2.303)/(27) log (100)/(12.5) = 7.7 xx10^(-2) "day"^(-1)`
`t_(1//2) = (0.693)/(lambda) = (0.693)/(7.7xx10^(-2)) = 9` day