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)Z`

Answer

C

Explanation

When an alpha particle `(._(2)He^(4))` is emitted, the mass number and atomic number of dougther nucleus decreases by four and two respectively. When a `beta` particle `(._(-1)e^(0))` is emitted, the mass number of product remains unchanged, but the atomic number increases by one. Therefore,
`._(n)X^(m)` overset (alpha)to `._(n-2)X^(m-4) overset (2beta)to._(n)X^(m-4)`