what particle is emitted in the radioactive decay 7433as→7434 se

the correct equation should be ⁷⁴As → ⁷⁴Se + e^-

the above decay is a beta minus decay,  a neutron change to proton, an electron and electron antineutrino is ejected.

 the atomic number or number of protons decrease by one while the atomic mass remain the same. the particle emitted is therefore an electron or precisely a negatron.