Final answer:
The balanced nuclear equation for the alpha decay of plutonium-239 is 239Pu -> 235U + 4He. The daughter isotope produced is uranium-235 (235U).
Step-by-step explanation:
The balanced nuclear equation for the alpha decay of plutonium-239 is:
239Pu -> 235U + 4He
Plutonium-239 undergoes alpha decay, where it emits an alpha particle (4He). The daughter isotope produced is uranium-235 (235U).