Answer :
Protons have a mass of 1
Alpha particles are Helium nuclei, so have mass 4
Beta particles are electrons, and so have mass 0
Neutrons have mass 1
Positrons are anti-matter forms of electrons, and so have mass 0
The answer is (3) a neutron
Alpha particles are Helium nuclei, so have mass 4
Beta particles are electrons, and so have mass 0
Neutrons have mass 1
Positrons are anti-matter forms of electrons, and so have mass 0
The answer is (3) a neutron