What is the product of the emission of a β particle by lead-212?

The emission of a β particle from a nucleus involves the transformation of a neutron into a proton, which leads to a few significant changes in the composition of the nucleus. When lead-212 undergoes β decay, a neutron is converted into a β particle (which is essentially an electron) and a proton is emitted. This process results in an increase in the positive charge of the nucleus because the number of protons has now increased by one while the overall mass remains largely unchanged.

This is pivotal as the increase in protons alters the overall atomic number, which defines the element. In the case of lead-212, this transformation results in the formation of bismuth-212, with an atomic number increased from 82 (lead) to 83 (bismuth). Thus, the emission of a β particle effectively increases the positive charge of the nucleus, confirming the accuracy of the answer.