In a radioactive series a nucleus X distintegrates into nucleus Y by emitting two alpha and two beta particles. IF m and n are the mass number and atomic number of the nucleus X, then the mass number and atomic number of the nucleus Y respectively are

Options

A. `(m -4),` n
B. `(m-8), (n-2)`
C. `(m-8)`, n
D. `(m-4), (n-2)`

Answer

B

Explanation

`""_(n)X^(m) overset(2alpha-"particles")to ""_(n-4)(X.)^(m-8) overset(2beta-"particles")to_(n-2) Y^(m-8), ""_(z)X^(A) overset(alpha)to""_(Z-2) Y^(A-4) ""_(z)X^(A) overset(beta)to""_(Z+1)Y^(A)`