What is the final nucleus after a series of radioactive decays?

[athenaroa]

modern physics

A certain radioactive nucleus has ' approximate mass' 212 and contains 92 protons. The nucleus undergoes beta decay. The remaining (product) nucleus, still radioactive, undergoes alpha decay, leaving yet a new nucleus. The number of protons in this 'final' new nucleus is:

 

[Blistering Peanut]

beta decay the atomic number is raised by one, alpha decay the relative atomic mass decreases by 4 and the atomic number decreases by 2.

 

[mathman]

91. However, there is no such beast. The lightest isotope of Uranium has 218 nucleons, and it alpha decays.

 

[swansont]

91. However, there is no such beast. The lightest isotope of Uranium has 218 nucleons, and it alpha decays.

Uranium doesn't have 91 protons. Protactinium does. I don't think the existence of the isotope is necessarily an important part of the exercise.