Respuesta :
A, B, B, D
Protons and neutrons have the same mass as far as mass number is concerned. A proton has a postive charge, and cancels that charge by absorbing an electron.
Correct answers :
1 - A) the mass number
2 - B) a neutron
3 - B) a neutron of an atom emits a high energy electron
4 - D) a gamma ray
Hope this helps,
Davinia.