B. the radioactive atom decays by alpha emission. write an equation showing the decay. (1 point)

alpha decay is an emission of ₂⁴He nucleus. If an element undergoes an alpha decay, the mass of the daughter nucleus formed is reduced by 4 compared to mass of parent atom and atomic number is reduced by 2 compared to atomic number of parent atom.

Let's assume that the parent atom is X, atomic number is z and mass number is A. Then the formed daughter nucleus, Y should have atomic number as z-2 and mass number as A-4.

The equation is

(z) (A)X → ₂⁴α + (z-2)(A-4)Y

Example:

₉₄²³⁹Pu → ₂⁴α + ₉₂²³⁵U