In this question, we need to determine what will be the nuclear equation for the Beta decay of Lead - 210.
Beta decay is a type of radioactive decay in which we will have either a neutron becoming a proton, this will be called Beta-minus decay or a proton becoming a neutron, this will be called a Beta-plus decay
In the case of Pb-210, we will have a Beta-minus decay, and one neutron will become a proton:
210/82 Pb ---> 210/83 Bi + electron
Lead - 210 will become Bismuth - 210