A radioactive nucleus A with half life T decays into a stable nucleus B. At t = 0 there is no nucleus of B. At some instant 't' the ratio of the number of B to that of A is 0.3. Then 't' is given by -
1
\(\mathrm{t}=\frac{\mathrm{T}}{2} \frac{\ln 2}{\ln 1.3}\)
2
\(\mathrm{t}=\mathrm{T} \frac{\ln 1.3}{\ln 2}\)
3
t = T In 1.3
4
\( t=\frac{T}{\ln 1.3}\)