The isotope 23892U decays successively to form 23490Th, 23491Pa, 23492U, 23090 Th and 22688Ra. The radiations emitted in these five steps are
A nucleus with Z = 92 emits the following in a sequence: α, β−, β−, α, α, α, α, α, β−, β−, α, β+, β+, α, The Z of the resultant nucleus is