Answer:
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
Step-by-step explanation:
Nuclei higher than Bi - 92 naturally are radioactive.
In a transmutation reaction, a new element is produced from an existing one due to radioactivity.
Nuclear fission is the radioactive process by which a heavy nucleus spontaneously decays into lighter ones with the release of a large amount of energy.
One example is the transmutation of uranium into thorium;
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He