The Nucleus — Physics STD 12 Science — Question

Consider a sample of a pure beta-active material:

1. All the beta particles emitted have the same energy.
2. The beta particles originally exist inside the nucleus and are ejected at the time of beta decay.
3. The antineutrino emitted in a beta decay has zero mass and hence zero momentum.
4. The active nucleus changes to one of its isobars after the beta decay.