Because the fissionable nucleus of uranium is ²³⁵U, the large quantity of ²³⁸U in a nuclear reactor isn’t used. However, it is possible to produce fissionable ²³⁹Pu from ²³⁸U by the reaction ²³⁸U (n, β^–) ²³⁹Np. ²³⁹Np decays by  β^–emission to ²³⁹Pu. A reactor used for this purpose is called a breeder reactor.

(a) What is the compound nucleus formed by ²³⁸U?

(b) Write balanced equations for the production of ²³⁹Pu.