Question

Nucleus has positive charge but in beta deacy the negative charge particle come out from the nucleus and no change in mass of the nucleus. Explain why?

Answer 1

in the nucleus of a radioactive element, where there is an excess of neutrons, a neutron changes into a proton by emitting an electron ( yes! u heard that right. a neutron is a compressed hydrogen atom). now the electron cannot remain in the nucleus, so it is thrown out with a great speed. and since the neutron has changed into a proton ( both with approx. same mass) there is no change in the atomic mass of the element.

hope this helps...