A hypothetical radioactive nucleus decays according to the following series:
`A overset(alpha)to A_1 overset(beta-)to A_2 overset(alpha)to A_3 overset(gamma)toA_4`
If the mass number and atomic number of A are respectively 180 and 72 then the atomic number and mass number of `A_(4)` will be respectively

Options

A. 69,171
B. 70,172
C. 68,172
D. 69,172

Answer

D

Explanation

`""_(72)A^(180)overset(a)to""_(70)A_(1)^(176) overset(beta^(-))to ""_(71)A_(2)^(176) overset(alpha)to""_(69)A_(3)^(172)overset(gamma)to""_(69)A_(4)^(172)`