A long-lived isotope of uranium, 92238U, is observed to transmute into 90234Th while emitting a single additional particle that is not detected by the experimental apparatus.
(a) Identify the emitted particle and write the complete nuclear equation for the transformation.
(b) Using appropriate conservation principles, justify whether the transformation you wrote in part (a) is an allowed radioactive decay. In your answer, explicitly address nucleon number, electric charge, and lepton number.