A nucleus `._n^ m X` emits one `alpha-`particle and two `beta-`particles. The resulting nucleus is

Options

A. `""_(n-4)^(m-6)Z`
B. `""_(n)^(m-6)Z`
C. `""_(n)^(m-4)X`
D. `""_(n-2)^(m-4)Y`

Explanation

When an alpha particle `(""_(2)^(4)He)` is emitted, the mass number and the mass number and the atomic number of the daughter nucleus decreases by four and two respectively. When a beta particle `(beta^(-))` is emitted, the atomic number of the daughter nucleus
increases by one but the mass number remains the same.
`therefore" "_(n)^(m)X overset(alpha)rarr ""_(n-2)^(m-4)Y overset(2beta^(-))rarr ""_(n)^(m-4)X`