Two radioactive substances `X` and `Y` initially contain an equal number of atoms. Their half-lives are `1` hour and `2` hours respectively. Then the ratio of their rates of disintergration after two hours is

Options

A. `1:2`
B. `2:1`
C. `1:1`
D. `1:4`

Answer

C

Explanation

No. of atoms of `A` after `2 hrs.=(N_(0))/(4)`
No of atoms of `B` after `2 hrs=(N_(0))/(2)`
`((dN//dt)_(A))/((dN//dt)_(B))=(lambda_(A)N_(A))/(lambda_(B)N_(B))=((T_(1//2))_(B).N_(A))/((T_(1//2))_(A).N_(B))=(2)/(1)xx(1)/(2)=1`