Final answer:
The half-life of 210 Po is 138 days, which is the time required for half of a radioactive sample to decay through the alpha decay process to become lead (Pb).
Step-by-step explanation:
The question asks to determine the half-life of 210 Po, which is a radioactive isotope of polonium. To find the half-life, we use the concept that in each half-life, the number of radioactive nuclei in a sample decreases by half. Although not provided explicitly in the question, we know from reference material that the half-life of 210 Po is 138 days. This means that after 138 days, a 10 milligram sample of 210 Po will decay to 5 milligrams.
For a more generalized formula, we use the radioactive decay equation: \( N(t) = N_0(1/2)^{t/T_{1/2}} \), where \(N(t)\) is the number of radioactive nuclei remaining after time \(t\), \(N_0\) is the original number of nuclei, and \(T_{1/2}\) is the half-life. In the case of 210 Po, it follows an alpha decay process, emitting an alpha particle to become lead (Pb).