The expressions for the Q values associated with both and + decay are given in Exercises

Question:

The expressions for the Q values associated with both β– and β+ decay are given in Exercises 20 and 23. Assume that the daughter’s atomic mass MD is the same in both processes.
(a) Use the β– expression to show that the requirement for decay to occur is simply that the mass of the parent atom be greater than the mass of the daughter atom, that is, Mp > MD.
(b) Use the expression to show that for decay to occur, the mass of the parent atom must be larger than the mass of the daughter atom by two electron masses, that is, Mp > MD + 2me.