Answer:
²⁰²Hg₈₀ ----> ²⁰²Tl₈₁ + ⁰₋₁e
Step-by-step explanation:
The radioactive decay of the atom of an element by the emission of a beta-particle is equivalent to the splitting of a neutron in the nucleus of the radioactive element into an electron and a proton. The proton is retained by the nucleus whereas the electron is emitted as a beta-particle. This retention of the proton results in an increase of the atomic number by 1. A beta-particle is an electron. The electron is a very light particle and its loss makes no significant change in the mass number of the atom involved.
The beta decay of Hg-202 results in an increase of the atomic number from 8-0 to 81. Hence, Hg-202 is transformed to Tl-202. the balanced nuclear equation is given below:
²⁰²Hg₈₀ ----> ²⁰²Tl₈₁ + ⁰₋₁e