Assertion :zXA undergoes 2 α- decays, 2 β- decays (negative β) and 2 γ-decays. As a result , the daughter product is z−2YA−8 Reason: In α- decay, the mass number decreases by 4 unit and atomic number decreases by 2 unit. In β- decay (negative β), the mass number remains unchanged and atomic number increaess by 1 unit. In γ-decay, mass number and atomic number remain unchanged