Answer Happy

A uranium-235 nucleus decays by a series of alpha and beta emissions until it reaches lead-207. How many alpha emissions and how many beta emissions occur in this series of decays? A) 7 a and 4 B decays B) 4 a and 7 ß decays C)5 a and 5 ß decays D) 7 a and 10 ß decays E) Cannot be determined