Answer:
barium-146
Explanation:
Beta emission is said to occur when a neutron is converted to a proton, an electron and a neutrino. Beta emission leads to a decrease in the Neutron/Proton ratio.
Beta emission is common for heavier nuclei having a large number of neutrons. Barium-146 has 90 neutrons, hence it is more likely to undergo beta emission than other nuclides stated among the options.
