In a balanced nuclear reaction involving polonium-212 (atomic number 84) releasing an alpha particle (which is a helium nucleus with an atomic number of 2), the reaction can be represented as follows:
\[ ^{212}{84}\text{Po} \rightarrow ^{4}{2}\text{He} + ^{A}_{Z}\text{Pb} \]
When polonium emits an alpha particle, the atomic number decreases by 2 (because the alpha particle has an atomic number of 2), and the mass number decreases by 4 (since the alpha particle has a mass number of 4).
So, the atomic number of lead can be calculated as follows:
- Original atomic number of polonium: 84
- Atomic number after emission: \(84 - 2 = 82\)
The mass number will also decrease by 4:
- Original mass number of polonium: 212
- Mass number after emission: \(212 - 4 = 208\)
Therefore, the lead produced will have:
- Atomic number: 82
- Mass number: 208
Thus, the correct response for the atomic number of lead is 82.