Answer
is: mass number stays 184, but atomic number changes.
Beta decay is radioactive decay in
which a beta ray and a neutrino are emitted from an atomic
nucleus.
There are two types of beta
decay: beta minus and beta
plus. In beta minus decay (atomic number Z is increased by one, new element is wolfram W) neutron is converted to a
proton and an electron and
an electron antineutrino.
In beta
plus decay (atomic number Z is decreased by one, new element is hafnium Hf), a proton is converted to a neutron and positron and an electron neutrino, so mass number does not change.
