Decay Processes of 39Ca, 39Ar, and 40K

[richphys]

Could I please check if my answers to the following three questions are correct? My answers are in bold.

1. How would you expect ³⁹Ca to decay?
a) β+ or electron capture (EC)
b) Electron capture only
c) β-
d) α

2. How would you expect ³⁹Ar to decay?
a) β+ or electron capture (EC)
b) Electron capture only
c) β-
d) α

3. How would you expect ⁴⁰K to decay?
a) β+ or electron capture (EC)
b) β-
c) α
d) Both β- and β+/EC

 

[mfb]

Wikipedia has lists of isotopes where you can check the answers, e.g. isotopes of calcium.