I cannot find the propositions, so I just define what an alpha particle is:
Alpha particles (or alpha rays) are a form of radiation emitted by unstable nuclei of great atomic mass (alpha decay). They consist of two protons and two neutrons combined into a particle identical to the helium nucleus, so they can be written 4He2+ (or 4α2+). (the nuclei will lose 2 positive charges and 4 atomic masses)
Unlike other particles, a Beta particle is the emission of an electron (or a position), and gamma rays (not a particle) is the emission of a ray photon very high energy light.
I hope this could help you with you answering the question.
