There are two radioactive substance `A` and `B`. Decay constant of `B` is two times that of `A`. Initially, both have equal number of nuclei. After n half-lives of `A`, rates of disintegration of both are equal. The value of `n` is .

Answer

1

Explanation

Let `lambda_(A) =lambda and lambda_(B) =2 lambda`. Initially, rate of disintergaration of `A` is `lambda N_(0)` and that of `B` is `2 almbda N_(0)`. After one half-life of `A`, rate of disntigration of `A` will come become `lambdaN_(0)//2` (half-life of `B =one` half the half -life of `A`. So, after one half-life of A or two half-lives of `B`,
`((- dN)/(dt))=((-dN)/(dt))_(B)`
`:. n=1`.