In a nuclear decay, a nucleus emits one `alpha`-particle and then two `beta`-particles one after another . Show that the final nucleus is an isotope of the former nucleus .

Explanation

`._Z^A p oversetalphato ._(Z-2)^(A-4)Q oversetbetato ._(Z-1)^(A-4)R oversetbetato ._Z^(A-4)S`
The atomic number decreases by 2 during `alpha` -decay and it increases by 1 for each `beta`-decay . So the atomic numbers of both P and S are equal to Z and hence they are isotopes of each other.