The radioactive nuclide `""_(90)""^(234)Th` shows two succesive `beta`-decay followed by one `alpha`-decay. The atomic nuimber and mass number respectively of the resulting atom is

Options

A. 90 and 230
B. 92 and 230
C. 92 and 234
D. 94 and 230

Answer

a

Explanation

During the emmision of `alpha` particle `Zdarr` by 2 units and `Adarr` by 4 units . During the emmision of `beta` particle `Zuarr` by 1 unit and A doesn t change
`2""^(n)=N""_(0)/N=(15.5-1.5)/3.5=4,n=2`