A nucleus `._Z^AX ` emits an `alpha`-particel. The resultant nucleus emits a `beta^(+)` particle. The respective atomic and mass numbers of the final nucleus will be

Options

A. `Z-3, A-4`
B. `Z-1,A-4`
C. `Z -2 , A-4`
D. `Z, A-2`

Answer

a

Explanation

`._Z^AX rarr ._2^4He +._(Z-2)^(A-4)Y`
`._(Z-2)^(A-4)Y rarr e^(+) ._(Z-3)^(A-4)Y' `
During `beta^(+)` emission,
`._TP^1 rarr ._0n^1 +beta^(+)`
The proton changes into neutron. So, charge number decreases by 1 but mass number reamins unchanged.