Question

State whether the following nuclear disintegration are allowed or not (star indicate an exited state). Give reason if it is not allowed.

\[\ce{^A_Z X -> ^A_{Z-2} X + ^4_2 He}\]

Answer 1

Nuclear disintegration is not allowed because mass number is not conserved. Emission of particles results in a 2 decrease in the atomic number but no change to the mass number, which is obviously impossible.