Potassium -40 can

a) Equations:

1) [β^- emission]

2) [β⁺ emission]

3) [electron capture]

b)

,

where c² = 931.5 MeV/u

case 1:

case 2:

Case 3:

Note: For energy calculations we use the masses of the nuclei of the reactions but as we are given atomic masses we add and subtract appropriate number of electrons to get the above expressions. For more details, one should look through the derivation of Q value for the three cases.