What is the product if an atom of po-209
undergoes alpha decay?

Lead-205 (Pb-205)

Explanation:

We are given;

An atom of Po-209

We are supposed to identify its product after an alpha decay;

Polonium-209 has a mass number of 209 and an atomic number of 84.When an element undergoes an alpha decay, the mass number decreases by 4 while the atomic number decreases by 2.Therefore, when Po-209 undergoes alpha decay it results to the formation of a product with a mass number of 205 and atomic number of 82.The product from this decay is Pb-205, because Pb-205 has a mass number of 205 and atomic number 82.The equation for the decay is;

²⁰⁹₈₄Po → ²⁰⁵₈₂Pb + ⁴₂He

Note; An alpha particle is represented by a helium nucleus, ⁴₂He.